I've reached out to psf/requests via their issue tracker (psf/requests#6211) to begin exploring why various projects aren't merging the type stubs from typeshed.

From requests, they've said that previous reviews of the type stubs are inaccurate and prevent them from merging the type hints into the main codebase.

This issue is to explore how type stub accuracy can be better evaluated to reduce the maintenance burden currently imposed on typeshed caused by inaccuracy or incompleteness.

Ultimately, while having stubs may help end users in the short term, inaccurate or incomplete stubs can prevent or delay long term adoption by the upstream team(s).