Not a new phenomenon in human nature or on the Internet, by itself. On some wikis (e.g. en.wikipedia.org) there used to be extensive lists of “notorious vandals”, then people realized that this only encouraged them further, now this is more limited, but there still is https://en.wikipedia.org/wiki/Wikipedia:Long-term_abuse

ffs stop feeding trolls and spammers

!superbowl@lemmy.world is already a thing, but I’ve said before and am repeating here that this is a lot less funny on a platform where “superbowl” on other instances can still be communities about the Super Bowl than on reddit where there could be only one “superbowl” subreddit

That is basically OpenID which has been around for a long time. In principle there is nothing stopping fediverse instances from being OpenID providers or allowing login with an OpenID, not sure anyone has done this yet though.

First of all, can people stop empowering, rewarding and encouraging spammers by starting threads about them?

My understanding is that many people in the US and Canada identify with their ancestry? Lots of Americans think of themselves as “Irish” for example, some of them may actually be immigrants from Ireland, others may have more-or-less distant Irish ancestry, so this is what may be going on here.

Everything posted on the public web is potential AI training data, federation is completely irrelevant to that.

The rest of your questions has the simple answer that a priori there is nothing “stopping” any of that. You should choose an instance whose admins are looking out for things like that and keeping your experience enjoyable, banning spambots or defederating from spambot farms when they are discovered.

What part of the fediverse is “hard” to use?

Lemmy is easier to use than the UBB forum I started to become active on at the age of 10 that was the entry point for me being on the Internet at all. Back then we didn’t have Markdown, but BBCode, and I had that figured out after a few weeks.

I think you’re way underestimating young people.