Please. Captcha by default. Email domain filters. Auto-block federation from servers that don't respect. By default. Urgent.
And yes, to refute some comments, this publication is being upvoted by bots. A single computer was needed, not "thousands of dollars" spent.
Because you shouldn't. Just like with other federated systems like e-mail or OAuth/OpenID, you don't create accounts everywhere, you use ONE account everywhere instead.
You should. Imagine e-mail server admins would start banning other e-mail services based on political or religious views and whatnot, that would fragment e-mail system and eventually destroy it. The only reason to defed other instance if such instance breaks the law. Just like we blacklist fraudulent mail server. Not because we don't like fraud, but because it's illegal.
I feel like the email analogy sort of breaks down. Email is point to point, not a forum. If there's a Lemmy instance community that acts like the equivalent of the_Donald subreddit and they go around harassing other communities I'd want to defed from that server. I don't want to try to block them one by one.
The benefit (and potential downside) of Lemmy is that there could be several networks of communities. There doesn't have to be a single Lemmy community, but there could many, all with different goals and guidelines. That definitely has pros and cons, but I come down on the opinion that it's overall a good thing.