> Wikipedia is not an authoritative identity layer, it provides no proof of identity and is thus strictly weaker than any other proof you can come up with. If you don't trust any arbitrary website that Wikipedia cites, then you have no more reason to trust any arbitrary Wikipedia editor.
It's the "strictly" with which I take issue. I certainly have no more reason to trust that a Wikipedia user whose username is BigImportantDude is actually a particular Big Important Dude than to trust the analogous fact about a blog post purporting to be authored by the Big Important Dude; but I dispute the fact that I should trust it less.
Wikipedia is not an authoritative identity layer, it provides no proof of identity and is thus strictly weaker than any other proof you can come up with. If you don't trust any arbitrary website that Wikipedia cites, then you have no more reason to trust any arbitrary Wikipedia editor.
As for what tertiary sources are and why they prefer not to cite primary sources in the first place, Wikipedia goes over this in their own guidelines: https://en.m.wikipedia.org/wiki/Wikipedia:No_original_resear...