But why does the world always go along with it? In an alternate universe, the community just said "yeah, no thanks, I'll keep using Gnome 2", which they continued maintaining under the name Elf or whatever.
They did! MATE is fairly popular, but as to why it happens I think it's about people.
There are only so many people willing (and able) to do the often difficult and unglamorous programming work that goes into maintaining something like Gnome.
If you're working on a major distro you have a certain level of trust in Gnome 3 because the same people delivered and supported Gnome 2. I'm sure when Gnome 3's direction became clear dozens or hundreds said "no way! I'm going to start my own fork which will never change!"
The sad part is that Gnome 2 had a whole ecosystem of third party software that integrated with it. Just a few of that got ported over to Mate (usually just s/GNOME/MATE/g) but it never gained the same traction.
I think that's where the fracturing comes in. For whatever reason, distros will ship with the new thing. The past 2 or 3 places I've worked adopted MATE (a continuation of GNOME 2). And, of course, there was instability at these places in figuring out which direction to go.
There are only so many people willing (and able) to do the often difficult and unglamorous programming work that goes into maintaining something like Gnome.
If you're working on a major distro you have a certain level of trust in Gnome 3 because the same people delivered and supported Gnome 2. I'm sure when Gnome 3's direction became clear dozens or hundreds said "no way! I'm going to start my own fork which will never change!"
But how do you know which one to pick?