Spammers, trolls, and ban evaders often use temporary email addresses. PieFed now checks a list of known temporary email providers and displays a warning icon next to registrations that use such services.
If registration mode is set to "Open" (no approval needed) then the site admin(s) receive a notification instead.
A throwaway email address isn't always a bad thing but it's one factor that admins might want to take into account.
Being concerned for the privacy of people as a whole makes me a prick?
I don't know why you assume that I don't contribute?
Why would it? Is it going to wipe those sites off the internet? No? That's why. Those sites will still be there, discriminating against users who just want privacy on the internet. That's like saying Lemmy solves the problems that Reddit creates or Mastodon solves the problems of Xitter. Those problems still exist because people continue to choose to participate in those communities, against their own interests.