3) It should be extremely easy for any Mastodon admin to opt-in to automatically updating deny list that blocks these worst of the worst instances. Most Fediverse instances don't have an updated deny list of these instances. It's too much work.
There are lots of folks working on this at the moment, and we're getting organized. I would bet that by the end of the year, the majority of Fediverse instances will be covered by a shared deny list.