I don't think rewrites were on the map for Perl, except arguably for Raku (Perl 6 as was) and I don't think Raku's developers were intending to throw away bug reports and just begin over next year, indeed even though Perl 6 failed in its original goals Raku seems to still be going.
I wouldn't classify any of the spectrum of language evolution strategies for popular languages as CADT, even Python where Python 3 was needlessly incompatible this wasn't part of some larger plan it just fell out from what they wanted to do and was then mismanaged. Getting to a place where strings aren't just "some bytes, who knows if they're human text, good luck" is difficult enough to justify a lot of pain on the route there, notice how C++ has tried and failed several times already.
Jamie was thinking mostly of things like GNOME where this was (is?) a big problem.