Do you not see how their current page takes design cues from professional pages?
I think its much more likely the greater volume of criticism is due to the fact that as OP gets closer to a known aesthetic, the precision of the criticisms can grow because it becomes more obvious what the goal is, and how its been missed.
Whereas a totally unstyled HTML page can't really be criticized usefully, because there is no real goal presented, and so nothing to really contrast against. At best you can say "fix everything".
> Sections are not delineated clearly
> separation between heading and body
Personally, when I open that site, I have no idea what it's about at all (yeah, it's something related to house-hunting). Only when I scroll down an entire screen-height, I get some high level explanation.
All the things you noted are there, but I don't think fixing them would solve anything.