Neat find, though it's funny to me that a phone number is something people (including everyone on this thread I bet) have been handing out like candy their entire adult lives - to friends, stores, banks, employers, government agencies, random websites – but still expect it to remain some critical secret that no one should ever find out. A phone number is about as private as your name, and you should consider it as su…
Uhh . . . this is not an earth-shattering take, considering they used to publish entire books with everyone's phone numbers and addresses in them, and you had to pay a fee not to have your number listed. Are we really to the point people don't understand the concept of a phone book anymore?
Do I expect it to be private? No.
You can for a small fee on some websites get my number.
Heck if you find a phone book from ~2000 where I use to live then you could just look it up in the phone book. Number portability saw to that.
Considering the number of data breaches and past history of phone numbers. To expect any sort of privacy is 'nice to have' but not going to happen. At this point it is basically security thru obscurity to expect it to be private.
Even when they had 'unlisted' numbers you could buy a book from the phone company that had it in there anyway. They even had reverse phone books you could buy. I even remember CD's from ~1998 that had the whole country. You didn't even need to keep the books.