The standard library is full of dead batteries. If the stdlib is so good, why does everyone install requests instead of using the stdlib http client? And why requests or something like it hasn't been adopted into stdlib after so many years of stability?
Parts of requests has been adopted into stdlib: https://docs.python.org/3/library/urllib.request.html
People mostly defer to requests because they do not track language development closely and because we are creatures of habit.
I try to avoid non-stdlib packages when stdlib will do a good job, but I received negative feedback from people who aren't aware of the updates and couldn't foresee supply-chain attacks.
Because the typical Python programmer does not appreciate the advantages of a slightly rusty stdlib compared to reaching for the bedlam that is PyPI.
You are picking one of the weak points of the standard library and an unusually popular replacement (and AFAIK it is built on the standard library). I cannot think of many others that are widely used. Maybe lxml ?
A Python codebase might well use requests, but it will almost always also heavily use the standard library.