"Phone[ ]book" is the 12th word on the page you linked, and described there as a synonym to "directory". There's no need to be that pedantic.
"A telephone book was a directory for telephone numbers" is clear and accurate. Unless knowing what the word "directory" means is asserted to be the domain of pedants.
"By providing a worldwide, distributed directory service, the Domain Name System has been an essential component of the functionality of the Internet since 1985."
It's quite pedantic.
I'm the same way, here's an interpersonal relationship tip I've had to learn: If someone calls you an asshole, you can't say "No, I've thought about it and you're wrong, you don't really think I'm an asshole." Well, you can say that, but it just makes you come off as even more of an asshole.
A straightforward search for the term brings up large sites in the UK, India, Malta and Hong Kong. "Directory Enquiries" was (is?) the name for the service in the UK where you pay a fee for someone to look in the telephone directory for you.
[0] https://images-na.ssl-images-amazon.com/images/I/51uCASmsWxL...
That is probably fair. Anywhere I've lived in the US, someone would know (well, maybe not if they were young enough) what you meant by "telephone directory" but almost everyone would say "phonebook" at least in casual conversation. It's also true that when you would dial 411 for a number, that was called directory assistance. (And a listing of phone numbers for the staff in an organization would probably be called a staff directory or a telephone directory or something along those lines.)