My best friend is planning her hens do and she invited me only on Facebook and didn't reach out to me personally. Would you say she is an acquaintance at best?

It's not so much about Meta itself but a social network can be very useful. It just so happens to be that the most popular one currently is Facebook. If someone decides they want to use and would benefit from the services a social network has to offer then naturally they're going to want to use the one that almost all the people they know are already using. No point using social network B while all your friends and family are only using social network A. That would be like wanting to party/socialise in the city at night but only going to empty bars and then scratching your head about why you have no one to talk to. You go to the bar that's popular. The choice of which one is already made for you if that's the kind of thing you want to do.

Don't get me wrong, I spend about a minute on Facebook a month, I find it very useful for events especially. Given the convenience of the tools available, I don't expect people to message me directly when they're organising a medium to large gathering.

Then they must break their own privacy policy.

To say it's a privacy nightmare in the context of a Google thread is just not accurate. If they associated search queries with your account then they'd be breaking their own privacy policy and opening themselves up to lawsuits.

No it's not horrible for privacy it's literally just for billing which payment can be made anonymously too. They don't even verify the email address you use. So much misinformation in this thread. Go Google your info before you present it as fact.

DuckDuckGo and Kagi are both hybrid search engines, they both have their own crawlers and combine their results with results from other sources.

I think you missed the point and focused only on the examples provided