I agree with this, but not the rest. It is not a security vulnerability, and I am not sure it being a privacy-sensitive endpoint either. Like someone pointed out, if you check one of your contacts and they have WhatsApp, you can tell, and you can message them from there. This is a feature.

I agree that there should be rate limiting of some sort.

Scale matters a lot for privacy.

For example, while everybody can physically go to your house and look at it from the street, somebody setting a webcam up and pointing it at the same house from the same vantage point would be a very different story and is illegal in many jurisdictions as a result.

If Whatsapp is banned in the country and you could get sent to jail for using it, I'd want the fact that I'm using Whatsapp to be kept private.

Sure, they probably should implement it to be able to make it private, but then again, I do not trust Meta and I do not think you should trust it either, so if you get sent to jail for using it, you should probably be wary of it either way.

There are many alternatives to WhatsApp, you may want to try them. Briar, Ricochet Refresh, Session, Matrix (Element), Jabber (with OMEMO and whatnot), among many others.