It are valid points. I tend to go offline for certain groups simply since it is getting very messy to be honest. I need to rethink my usage of the fediverse to be honest.
Those are hidden too over here so I can't respond. Indeed an rbl is not to hard to build but I have a lot of other worries about how the fediverse interacts. I now have a nice balance when it comes to people who are posting a lot that does not interest me but do post items I would like to see. Filters per user help out a lot to be honest. Anything that is simply forwarded is not shown in my stream since it are mostly mem reposts of memes.
As for Spamikaze, it works great as an rbl but I doubt it would work for the fediverse. A lot of people hate the idea of it ( same as a lot of isp's who got blocked by it ).
There are those incompatibilities between #mastodon and various other app types. Where I mostly notice this is when replying to Bob of #Epicyon. Then manually adding in other mentions on the thread is often required.