I still to this day stumble upon code I have to use 2.7 on, thankfully things like pipx make it easy these days. but still,switching back and forth could be a pain.
But you're right, it wasn't like Perl 6. People moved to python and php mostly from perl. what were going to move to from python 2? Ruby?
In 2018, I don't know if Go was a major player, both it and rust were still new-ish languages. There was still a concern of being able to hire devs if you used them, where as not so much in the past 4-5 years.
~3.8 at the time, not 3.0. 3.0 was a mess.
There's always Tauthon (Python 2.8), lol.