Perl 5 -> 6 broke all your code in exchange for a whole new language. Some people moved to Perl 6, some to other languages, and a lot stayed with Perl (5), which still runs programs written in Perl 1.
Ruby 1.8 -> 1.9 broke most of your code in exchange for minor cleanups. But Ruby was Rails, so the culture accepted constant rewriting and breakage, and people went along.
Python 2 -> 3 also broke most of your code in exchange for minor cleanups. Users expected some stability, but the language's culture demanded conformity. The result has been a decade-long war in which Python fans try to shame Python users into moving to version 3.
The main reason people switched probably wasn't rails making people expect breakage, the main reason was that (a) it was relatively easy to rewrite your code to work on both 1.8 and 1.9 (as long as your dependencies had already done it), and (b) 1.9 was much faster.
I think that's the most succinct way to put this whole debacle I've ever seen. I'm totally stealing this.