The people who haven't upgraded to Python 3 in their projects are probably mostly people with dependencies on py2.7 libraries. Happened to me in my last project. I started using pypy until some bug in pypy prevented me from using an important package. Switched to python 3 until some other dependency wasn't available. So it's a pity, but i was more or less forced to use py2.7 (without putting major effort into 3rd party libraries).

And you did put at least the same amount of effort as to write this comment to report the bug to pypy devs and/or library devs right?

How often do people do that for CPython?

Less often because CPython characteristics are well known and there is no baseline to compare to.