I think it makes perfect sense as a general and strict policy for an encyclopedia. It would simply be too hard to audit every case to check if it's someone like you, or a crank.

Joke aside, I should probably take up on your advice.

Basically, Wikipedia wants a primary source's claims to be vetted by a third party, either a "reputable publisher" or a secondary source.

But why is a reference to "[1] Blog post by XXX" (or, even worse, "[1] Blog post by YYY based on their tentative understanding of XXX") a more authoritative source than "[1] Added to Wikipedia personally by XXX"? Of course, Wikipedia potentially has no proof that the editor was actually XXX in the latter case; but they have even less proof that a blog post purporting to be by XXX actually is.

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...

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.