Good question! We just shipped GitHub Discussions to millions of developers and we can learn whether people use and like the product by looking at whether people are creating discussions, customizing categories, and answering questions.

The argument that you need to follow users around every step of the way to build great products is simply untrue.

I’m sure that GitHub certainly has analytics; they just don’t use third-party analytics. This means that either they’ve built their own tool or are self hosting someone else’s. I imagine that GitHub has some amount of internal tooling here out of necessity, e.g for metrics about how people use GitHub over SSH.

By looking at http access logs, like since the beginning of times? Note if by modern sites you mean SPAs, you could still make HTTP pings for those features; might not make much sense to use SPAs for content-driven sites though.

You could still self-host an analytics solution. Just don't share that data with 3rd parties.

It doesn’t mean no analytics, it’s about including third-party analytics scripts. You can still do analytics.

You can use analytics programs without needing cookies. I use Fathom (usefathom.com) and they are compliant.