The motivations seem pretty plain. They were anticipating the question, "why did you host this site yourself?" I don't think there's any need to read further into it. You seem to have come to that conclusion yourself.

The HOA analogy would be appropriate if HOAs were about conduct among colleagues. It's pretty obvious why you need to set ground rules when you have a huge number of people collaborating - you get incidents of people behaving inappropriately, and if that behavior proliferates, you will create a hostile environment where it's difficult for work to be done. (See this comment https://news.ycombinator.com/item?id=43147705)

HOAs are a problem because there is very little shared interest in regulating the size of hedges or the color you may paint your house or whatever. It's a scheme to keep property values elevated.

There is no connection between these phenomena. One of them addresses pragmatic and real problems, however flawed the implementation may be. The author is a scheme to manipulate property markets. There is no shared cause between them.