Most people who had bigger Python projects simply could not upgrade because they had a whole bunch of dependencies that did not work under Python3 and that coul

Most people who had bigger Python projects simply could not upgrade because they had a whole bunch of dependencies that did not work under Python3 and that could also not easily be replaced by some other library. On a big python project at work we only very recently have lost our last dependency on a Python2 library and it took some dedicated effort to track and replace these dependencies. And upgrading all of our own code to be Python3 compatible will be a whole other can of worms (even though we were careful to write our code in a forwards-compatible way using future imports etc.).