Then again I've got Perl code I wrote in the 90s that still runs untouched on the latest Perl 5. Much more recent Python 2 code (of mine) still won't run untou

Then again I've got Perl code I wrote in the 90s that still runs untouched on the latest Perl 5. Much more recent Python 2 code (of mine) still won't run untouched under Python 3. So I might agree actually on the "bigger", but the "noticeability" does have a lot to do with the general feeling. (to be clear, I agree with all of your comment)