In the search link I posted above, there are lots of explanations of this, for example https://news.ycombinator.com/item?id=17996295. The point is that HN is a community and a community consists of people relating to one another. The fact that you can pick whatever name you want and it needn't be your real one doesn't change that.

It's also the way HN has always worked. A collection of nameless posts would be a very different kind of forum. Anyone is welcome to start one, but not to turn this one into that one.