Not only that, but we also know that no one pattern matcher fits all: with or without segment patterns? how to designate pattern variables? should it be extendable? what would we actually be matching? should we actually use a unifier? etc. Pattern matchers are easy to write, anyway.

We also know that they don't always make things clear, so we don't use them everywhere. Programmers using languages that have a pattern matcher "built in" tend to use it all the time, and it's not always a pretty sight. I conjecture that with this addition, Python codebases will become dichotomized: either it will be used everywhere, or it will not be used at all. The latter obviously has a head start :)