Censorship of npubs can happen too. It's just usually going to be in the interface layer. If there was name registration on the chain this wouldn't be a problem too, but name registration and resolution systems are not an easy problem to solve.

I had the idea of them being mined with a difficulty adjustment and the name has to appear in the target in place of the zeroes in the bitcoin difficulty adjustment scheme recently. It could be slow enough that there is usually only a dozen or so new ones each block. Something I've got in my mind for future work somehow.