At least IMO, the neat thing about these isn't a privacy thing, it's that when you don't have an identity associated with the usage of your service, you have to

At least IMO, the neat thing about these isn't a privacy thing, it's that when you don't have an identity associated with the usage of your service, you have to answer some interesting questions (data persistence? Rate limiting? Cost, or is it low enough that it can just be free for everyone anonymously? Etc) which make the solutions fun to check out