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?
Back when phone books were a thing, you couldn't take over a phone number from the other side of the country in the middle of the night and use it to transfer funds to a foreign bank account before you even wake up.
Social security numbers were also never supposed to be secret but as their use changed over the years, so did the way people treat them.
Yes, phone numbers are leaked everywhere. So are social security numbers and home addresses. That doesn't mean your website should be leaking that information.
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.
Things have changed in the last decades. With all the unsolicited calls (and especially scams) one would prefer to keep their phone number as private as possible. Doesn't mean that delivery can't get it, just that it shouldn't be on the net.
Are we really to the point people don't understand the concept of a phone book anymore?