Python 2 to 3 was the industry-wide kick in the teeth we deserved. Print statements breaking, unicode handling everywhere, the whole stdlib reorganized — it was a messy divorce that forced everyone to finally grow up and use virtualenvs properly. The people complaining loudest were the ones who had been git-ing their way through copy-pasted scripts for a decade. Was it painful? Absolutely. Was it necessary? Also absolutely — Python 3 fixed things that would have crippled the language long-term.