The AGPL was a good attempt but it seems that it too vague. For example even Google, with its teams of lawyers doesn't feel comfortable using it for any purpose.

https://opensource.google/docs/using/agpl-policy/

It appears that they are concerned that it may be argued that if for example YouTube uses an AGPL DB that they would be required to release YouTube under AGPL.

I'm not saying that the interpretation is correct, but if companies can't be sure they won't use your software.

And to be honest IANAL but their interpretation seems reasonable to me. If you put Mastodon behind NGINX I think it is fairly easy to argue that the user is "interacting with it remotely through a computer network". So now if you have a theoretical AGPL Elasticsearch and your site sends the user search query to it and returns the user the results it doesn't seem clear that this is a legally meaningful difference. I certainly wouldn't want to argue that in court. I'd just use different software.

Stallman will break all sorts of records for being “the most annoyingly correct forecaster of computer trends with the less affable personality ever”.