Everybody uses it, so there must be a reason it is needed /s

I've asked that question quite a few times as well, and for most of the people I've had this conversation with, GA simply IS how you get metrics and insights, whether you're interested in anything advanced or just the number of pageviews, GA is how you get that in the same way as a hammer is how you get that nail into the wall. Plus it's well-known and relatively easy to troubleshoot (since there is a youtube video for pretty much any edge case), all the tech people know GA so chances are you won't have to troubleshoot much. There's also the ecosystem of tools and third-party products that tie into GA or GA BigQuery exports, that's also very important for some people as you can build some pretty impressive yet scary rube goldberg machinery out of GA and a bunch of these.

It's easy and people are lazy.

Mostly vanity, for most people. Essentially it's a grotesquely mutated website counter. "17348 people have seen the site I made".

Agreed. I really like CloudFlare’s built-in serverside analytics.

Fathom takes privacy pretty seriously - they're still somewhat early stage in terms of functionality, but a great place to start.