Surely is more about slow evolution than revolution.
I personnally totally saw it as a different project as gnome 2 didn't become obsolete immediately and Mate&Cinnamon forks took over so quickly for those looking for a gnome classic evolution that no one was really forced into using gnome 3.
Yeah it did. They announced gnome 3 and deprecated 2 on the same day, and seemed to have made the deliberate choice to not allow them to coexist. As soon as your distro moved, bam, you were done.
> Mate&Cinnamon forks took over so quickly
After some months. This stuff was not there on day 1.
In the mean time, those of us who did not want to work the way Gnome 3 decided we should, had to find an alternative. And when we found a good one (Xfce for me), we stuck with it.