@futurebird The advantage I find more in Mastodon is the possibility to change of server. Different of main stream social media like if I have a Twitter account and wanted to migrate to other site, I need to start from zero where many people feel a very unpleasant to lose all contact.
At least in Mastodon have a "framework" in common, so if some server has rules I doesn't accept, I can move to another server, so I doesn't stay locked by one server. At least in harassment and similar need a lot of effort between servers admins and their users to block, but it's possible.
Now on spam side, this I don't know how to, put a limit to been approved before can send a DMs or PMs, or need a vote to decide to blacklist some server.
For now, the best is deal what we have in our hands now and see if someone with more experience or interest in create a new API like Mastodon where it's deal with spam and harassment. This is the fun part of a FOSS, right?