> "here's a copy of my entire phone book"

I don't know how or why that was ever legal in the first place, and why Facebook and LinkedIn haven't been sued to death over it.

The contacts-matching system is how Facebook and LinkedIn'ss ultra-creepy "People you might know" list works, and I have no-doubt this will have led to things like journalists' confidential sources being discovered and harmful outing of closeted people, and worse.

I’ve never uploaded my contacts to FB but it still recommends people I worked with or met 20 years ago because they uploaded theirs.

Extra evil because you can be triangulated from the uploads of many naive people, so essentially they win in the end.

Same situation with DNA. I may avoid getting an online genome test, but once a couple cousins send theirs in I'm basically a part of the network at that point

Not to encourage you to use whatsapp but on android an empty work profile is nice for this use case.

I just use OpenContacts from F-Droid and leave my phone contacts empty. OpenContacts has a extra button to open a contact in Whatsapp.

GrapheneOS has a feature called contact scopes[1] that lets you pick which contacts apps have access to. It's great!

[1]: https://grapheneos.org/usage#contact-scopes