Acknowledging your privilege is not categorically virtue signalling. One can think there's not value is acknowledging privilege (or that it might not exist), but let's not pretend it's impossible (or unlikely) that another does.
I think it's very telling that folk think that writing "I'm saying this from a position of privilege" invariably is done with a proverbial gun to their head, hoping to evade a public flogging if they fail to do so.
People, myself included, genuinely see disclosing your position of privilege in the same way someone from Company X might say "Disclosure: I work at Company X" when commenting on a post about Company X. Now, it might seem that acknowledging ones privilege is shoe-horned into every conversation, but I challenge you to think about how privilege touches so much of our lives.
Anyways, all I'm saying is you don't have to "find value" in folks acknowledging privilege. You just need to be able to imagine a world in which they do.
If one mentions it in a genuine way that is contextual to the discussion, then it is entirely appropriate. But if it is blithely and thoughtlessly tacked on to a preceding statement (which, let's face it, happens), then it gradually becomes a platitude and empties the acknowledgement of any charge or primacy when others are mentioning their privilige in a considered and good faith way.
Almost everyone is privileged in some way. I, personally, don't need to know whether someone is privileged to evaluate and understand their opinion. But on the other hand I agree with you that some people do in fact want to see this context attached to every post.