I want to understand why Automattic developers decide to only allow a handful of tag in comment section, or making it more intuitive. Is that on-topic? This doesn't seem to be addressed in What topics can I ask about here?
First, this isn't a decision made by Automattic, but by the WordPress developers. Partially the same people, but a different group nonetheless.
Second, you can usually read the justifications in the Trac tickets for the component. Just copying these over to our site wouldn't be that useful.
But generally, yes, you can ask such a question on our site. We had similar questions in the past, for example about the SVG format. The "intuitive" part of your question would probably be too much "primarily opinion based", but the selection of allowed HTML elements is not. My guess is that the answer is: "only the absolutely necessary" for security reasons.