While Evil mode is good, it is not true vim. That could be one particularly strong reason. There is also performance, emacs is slower than vim, unless you set up an emacs daemon at startup.
As a vim user of 25 years before switching to Emacs+Evil, I can name only about two things.[1][2] And they're not nearly enough for me to go back to vim for.
[1] - vim's \zs regex pattern, which would let me position the cursor ahead of where the regex match would normally take me without it. This can be very useful for certain macros, but I don't encounter an absolute need for it very often.. but when I do, I wish this was possible in Emacs.
[2] - In my experience, vim has been much more performant on large files with long lines.. but, again, I don't edit such files often enough to make me want to back to vim... and, anyway, when relatively rare cases when I do need it I can fire up vim for that one use.
Still nothing major, though.
I keep trying to use and learn emacs. It'll happen eventually.
One thing that's eluded me howver is being able to have graphical and terminal emacs work with the same daemon.