I don't see why we care about changing this. It reads well and allows a personal touch like a guided tour.

There is more of this. See #62480.

Borrowing some of the discussion on Diataxis, I think whether first-person pronouns belong in documentation depends on how the documentation is structured.

If it is the case how-to/guides and tutorials can be personal, and references impersonal (say like Wikipedia articles), then it seems acceptable that a page of documentation (pages under /library) that blends guides, tutorials, and references may have a blend of first- and third-person pronouns, as in the referenced unittest.mock.

If it's the case that documentation shouldn't have first-person pronouns, then perhaps documentation should explicitly split these guides, tutorials, and references into their own pages, somewhat like logging.