I guess I'm dating myself, but didn't we used to call that the phone book?
Nowadays one or a few phone numbers are unique to you, which makes it linkable to other things. Linkability is something that breaks privacy, so if you don't want your full name to be known somewhere, it is important to be able to keep things separate. When your phone number goes public (e.g. resumé and snapchat), that anonymity is broken.
Now generally it's advisable to use a unique handle (or your real name) for a service so closely tied to a piece of real life identification like your phone number, but I don't think a lot of people do it.
In the specific case though, it's as if you had already asked to be removed from the phone book (implicitly trusting the company), and then your number was published anyway.