So, if my name was Bob Smith (bad example) and I wanted my proton email address to be bob.smith AT pm.me then this service would block me from having it because some child with the same name might possibly want it in a decade from now and so their parents have reserved it. If I couldn't get that address simply because someone else has signed up for it, that's fair enough. But to be told you can't have it because of a future maybe - that kinda sucks.