ActivityPub is indeed a W3C standard; it's what connects together what's called the "federated social web" today. (Mastodon, Pleroma, Peertube, etc etc etc...) I am co-author of the standard. Spritely is a series of subprojects, ultimately building on top of, and extending the capacities of, the federated social web.
But my point was that when beginning work on ActivityPub as a standard, the kinds of comments on here were similarly negative. Of course you're not going to get a universal social network standard! Nobody's been able to do it, it's just out of reach. Might as well give up now.
Of course, now that ActivityPub has succeeded, people take it as a given that it was going to succeed. Criticism instead moves to certain design decisions, and that's fair and warranted. But hindsight makes those things that have been done seem as if they were always going to be done.
But at a time, it looked like ActivityPub itself, the thing we do have, could not possibly succeed, and people told me as such in many places, especially on here. Nobody questions that it happened now of course. So now I am proposing a multitude of layers in which we can make things better.
But it hasn't happened yet, and so of course the response is going to be, once again, that of course it's not possible...
So, Spritely isn't just an end-user thing because it's multiple layers, though a few of them are end-user layers (it's more of a laboratory for advancing the federated social web). It's true that it isn't a web standard itself, even though it aims to enhance the ecosystem that uses that web standard. But the point is: it's really demoralizing to get these kinds of comments, but they're the most common kinds of comments one gets on HN. Sometimes I did think about giving up on ActivityPub standardization. Ultimately I'm glad now that I didn't. So I think we can do cool and interesting things here with Spritely, and my lesson from the past is to not give up now either.