What advantage does bringing ActivityPub to this blogging platform have over just subscribing via an RSS reader?
My instinct is that there needs to be a second layer reputation system for recording which sites can be trusted not to inflate their like numbers. This becomes similar to the problem of which mail servers can be trusted not to send spam, but perhaps if posts and likes are public (unlike emails) then more useful reputation systems are possible.
[0] https://baptiste.gelez.xyz/~/PlumeDevelopment/this-month-in-...
One identity may refer also to running your own server, then you're safe from any extinction events :)
I think it's a cool idea. If you really want to break the power of FB, you need a way to easily see what people are reading, recommending, talking about etc. and that includes following a whole website, whether written by an individual or a corporation.