I always think about the post I saw a while back that was like “I use KeepassXC, a fork of KeepassX, a port of Keepass”. That seems very likely to be true in regards to the fediverse as well.
But I think that’s great, as a contributor to one platform I don’t necessarily see it as “one software above all”, which might be bad to say, but more like we’re all sailing on the much larger ship Fediverse, and it’s been great to see so much back and forth between the different ones, for example one person helping get pixelfed’s avatars federating, or piefed’s blogs, which helped reduce page load sizes for mbin by 40%. It’s quite possible we’re all just slowly contributing to a lot of learned lessons for a yet unstarted software.
All that said, mastodon does have a ton of staying power, as you said. Once they fully support groups, and lemmy has stated they never plan to support microblogs, it’s quite possible that mastodon will be a very solid experience for most of what people are looking for.
This may come close to what OP is looking for as it includes reasons for the tags such as
goreorspoiler