There are so many counters to this though.

Excluding things like dash, you have preps that wake you, mobs that will track and wake you (I've seen this done by a character repeatedly), preps that will keep you alive after a teleport, preps to cure blind and then use other preps etc.

Plus if someone fails the sleep attempt you can often kill them.

If someone is spamming, and you think they are prepped, you can walk away and make them waste preps so they prep less in future.

Also, you know you get sleep resistance if they fail the first attempt? It's pretty effective.