I really don't use semi-colons too often on the internet. I may use them in a more formal setting, but I don't consider an internet forum to be that formal. I think they are considered pretentious because most of the time they are forced. I believe most of the time it is more natural for both typing and reading when semi-colons are not used. They are rarely required, and most of the time when they are, there are much easier ways to phrase what you are trying to say.