dealing with incoming spam is just way more work than paying to have it hosted.

The right way to deal with spam is not to use filters in the first place. It’s not like Gmail or Proton or <insert your favorite email provider here>'s spam filters are perfect either, far from it, they still let a ton of shit through. The right way to deal with spam is to use unique aliases for each account that you can shut down if they leak.

I don’t have any problems with building beautiful things like cathedrals or making art in the name of God

What about Catholics praying to little figurines and statues of saints? Because that’s been going on for a long time