There are now many sites that do that. And as you ban people, people who perhaps would donate, you encourage longer donation cycles, which are getting longer, why is that? Now this site can go Darwinian if it pleases, some will still use the links to original citing.
Now you can make them poster only, that`ll only encourage those to leave and not visit at all, further marginalizing this site. I don`t care, I`m after the info, and not an acolyte of this site or any another, so do as you please, the free-market, such as it is, will still decide.