Quitting Meta means not getting to be in those circles anymore.
Basically you're subject to the lowest common denominator.
Message contents also aren't the only kind of data that Whatapp knows about. Facebook doesn't need message contents to monetize your communications. They almost certainly harvest Whatapp's metadata and tie it to everything else they know about you.
If you like the service, that's great. Use it and enjoy. But don't assume that your communications are secure.
WhatsApp encryption is strong enough to defeat criminal investigations in my country. That has to count for something. They got so angry about it they blocked WhatsApp services for days and jailed Facebook people.
https://www.forbes.com/sites/abigailtracy/2016/05/02/whatsap...
You can always return the contempt by extracting all our data out (provided that's important to you) and permanently shutting down you account. I believe that's the most efficient thing you can do to tell FB to go to hell.
Edit: I honestly believe that any FB user this is the most harmful thing you can do to them.