Well, that's actually a dumb question. There would be no schism whatsoever if everything hadn't changed with the advent of gnome3. At the end of 2010, there was gnome 2.3 and it was awesome. It was light, attractive and extremely customizable.
With the introduction of Gnome3, from the very get-go, we had no less than 4 options: Gnome Shell, Unity, Unity 2D, and gnome classic. Despite all of the choice available, many users (myself included) found themselves as desktop refugees, forced from their familiar stomping grounds to new, strange territory where things that used to work didn't work anymore. Things that you used to be able to change, you couldn't change anymore. The Gnome desktop lost virtually all of it's customizability, making simple things like changing your metacity theme nearly impossible.
In response, the community of users fired back by doing one of two things: either jumping ship and crossing over to another DE like XFCE, KDE, LXDE or Enlightenment. And in turn, devs fired back by creating even more forks and even more division. Practically overnight, we went from Shell, Unity and Fallback, to having Shell, Unity, Fallback, Shell with MGSE (Mint Gnome Shell Extensions, now defunct), Cinnamon and MATE. Oh, what a tangled web we weave...
Each desktop environment has it's own strengths and weaknesses, each one catering to one very specialized portion of the Gnome user base, and seemingly ignoring the rest.
I will make no bones about it; first of all I have strongly disliked both Gnome Shell and Unity from the start. In my honest opinion they are both poor implementations of what I expect from my desktop. In their defense, they are both continually improving and becoming more stable, faster and generally more usable. But they both sorely lack the customization of Gnome 2, and it seems they have no intentions of ever implementing it, adopting a "This is what our desktop is" policy, akin to the WYSIWYG lack of customization in Windows and OSX without the use of third party software.
I have tried and also strongly dislike MGSE when they were around, Cinnamon and MATE. My issues with all of the above is that they are all essentially the same thing. And yet none of them are terribly good at any one thing.
In my opinion, MATE, a fork of the old Gnome 2 desktop built on top of Gnome 3, while a valiant effort will eventually run its course. As Gnome 3 diverges further from the Gnome 2 codebase, eventually porting MATE will become impossible, or at least very resource prohibitive. We've already seen this happen with Trinity, a port of KDE3 in response to KDE4 and Trinity, although it enjoyed a brief meteoric rise to prominence with the release of KDE4, it has rapidly fallen in obscurity. Practically no one uses it anymore. And history will repeat itself in the case of MATE. MATE enjoys a niche market at the moment, but will eventually go the way of Trinity, Pet Rocks, Disco and Dinosaurs in my honest opinion.
Call me a purist, but I don't believe that any fork of the Gnome desktop is bound to gain any kind of permanence in the long run, and such diversions from the rest of the Gnome ecosystem are ultimately hurtful to the Linux cause. Instead of working together as a united community to make one great desktop environment, it seems that everyone is hellbent on forking dozens of mediocre ones. Without trying to start a flame war, make no mistake: I include Unity in that category as well. Although Unity is inextricably part of the Ubuntu brand identity now and it is probably not going anywhere, Unity's existence is ultimately hurtful to the Gnome community, not that Canonical cares -- they want to Ubuntu to by synonymous with Linux.
Personally, I am a user of the good old fallback session. It has certainly had it's growing pains since the release of Gnome 3, but today is really is stable, every bit as light as XFCE4, and albeit only through the use of increasingly confusing Gconf and Dconf settings or conversely with the use of third party tools like Gnome Tweak Tool and Ubuntu Tweak, I can get back to something resembling the work flow I had with Gnome 2.
And just when I thought there could be no more schism in our already fractured little community, there are two relatively new projects that have caught my eye; Elementary OS and the SolusOS Consort Desktop.
Both Elementary OS and Consort are yet more examples of unnecessary forks of Gnome 3. The reason why Elementary has caught my eye is because of how many things it is doing right. The focus, from the ground up is on beautiful, homogeneous design and simplicity. Every app that is part of the Elementary desktop (called Pantheon) uses a specialized window manager, cohesive system wide theme and key design elements. But what EOS lacks is flexibility. But then again, they aren't trying to be Ubuntu, or Windows or OSX. Their aim is to provide a simple, elegant and uniform user experience, something that has always been sorely lacking from even the most robust Linux distributions.
Consort Desktop is much closer to the upstream code of Gnome 3, originally starting out as a collection of patches to some key Gnome fallback elements, but over time they have diverged enough to where maintaining the patches became cumbersome enough to warrant yet another fork of Gnome code. Immediately, my knee jerk response is to groan and just go back to using my Frankenstein Gnome Classic desktop and just wait until this all blows over.
But Consort isn't just another fork. There are so many things that Solus OS (the distro that Consort is part of) does right. First of all, Consort ditches both Mutter and Compiz along with all their bugs, instability and CPU punishing glut, in favor of extending Metacity's lithe and fast compositing capabilities with modern features like window snapping (grid plugin on Compiz, built in feature on Kwin, part of Windows core functionality since the release of Windows 7).
Yes, both Elementary and Solus have managed to catch my eye. Not to the point of warranting a permanent distro hop, but certainly enough to throw each on virtualbox and kick the tires. Ultimately, I'll be sticking with Ubuntu and Gnome Fallback with a simple Compiz configuration for the foreseeable future. In the long run I think that despite what they may offer to the community, most of these desktops are just a fad. A few years from now when the dust settles, I sincerely hope that the ideas and developments from each of these little projects can be neatly folded back into the upstream Gnome ecosystem and we can once again have a united front, without all of the schism. Because right now, Gnome 3 feels like development in any one unifying direction has come to a screeching halt, and development and design decisions are being made not necessarily based on what is best for Gnome or the community, but based on personal agendas and a stubborn refusal to admit that what we have right now simply doesn't work.