- if you want to have comments or backtracks, you can do it with ActivityPub without having people signing up to your site (directly or through some OAuth system)
- If you want to mitigate spam, you can set up your AP blog to only accept messages on the inbox from actors who you whitelist.
- You could have your own Substack where you only send the updates to actors who are paying subscribers.
You can do the same thing with RSS+We mention, which is a way simpler stack and predates ActivityPub by years
Anyway, my point was less "ActivityPub can do everything people can do with RSS" and more "having a mechanism to for bidirectional authenticated messages opens up the possibility of new applications".
The real interesting part will happen when/if more developers realize that ActivityPub can do more than "federated versions of popular social media platforms".
As far as spamming goes, I don't see how WM is any worse than AP. In both protocols your only options are passlists and/or blocklists.
[0]: And an old version that doesn't have an official spec. ActivityPub's issues with spec stagnation and de facto standards is a whole other thing.
Perhaps more advanced URL regex can achieve more fine-grained control but I do still see advantages in pubkey auth (especially if people want to move their content.)
Still, I do find myself wishing for a lighterweight-than-ActivityPub middleground.
I suspect this is because WM is used far less than AP. It also grew out of a community (IndieWeb) where having your own domain is a core tenet.
I think something like Mastodon could work with WM though, since all URLs hang off of user URLs, so you could block by URL prefix, ie "block https://example.com/user1/*".
I guess one danger is that they only serve the page that contains your link to the webmention-validating request. That way they get a backlink but don't have to keep a public outgoing link. They'd have to know that a given request is that validation though, and I'm not sure that'd be very easy.
Regardless, my underlying point really is about what I expect of a microblog. If I'm hosting it myself I just want it to be my little corner of the internet, not a full fledged social media site that I have to maintain. That doesn't mean I'm right or that others don't expect more.
I think the problem is that OP is focused on developing a framework for AP, and he is dogfooding it by developing an application that other people can understand without too many new concepts.
This is good if you want people to get experiments, but it is terrible as a way to present the true potential of the protocol: https://cosocial.ca/@evan/113143389340566731