The pseudo-intellectualism that permeates this board is a little appalling. I can certainly assure you that C-level executives across Silicon Valley backed by the strongest VCs and beyond write in a much less formal manner than most people on HN. Nothing wrong with that.
Writing in clear understandable language and suggesting others do the same isn't "pseudo-intellectualism". It's just common sense. If you want your thoughts to be understood and respected, choose appropriate language to express them.
What people use in frequent communication with their friends or colleagues is likely to be different to that used on a public message board which brings together people from many different backgrounds for discussion of "deeply interesting" topics.
Context is very important, though. I don't think anyone is claiming that there is a correlation between intelligence and writing ability; only that within the context of HN comments from the majority of posters, style is important.
I suggest a study program in social signaling, but I'll summarize the relevant part:
People of unknown status must provide a signal that their status is appropriate enough to warrant respect and attention: if you're taking your Valentine's date to a Michelin 3-star restaurant, you wear your best clothes.
People of known high status have the capability of signaling their status in a seemingly perverse way: by countersignaling. When a movie star shows up to a Michelin 3-star restaurant, he wears jeans and a faded t-shirt to show that he's high-status enough to break convention there.
tl;dr: C-level execs backed by the strongest VCs have earned the right to write informally and still be taken seriously. Most of us have not.
