A popular tactic among a certain class of blogger is to write posts that are clearly designed to be linkbait, and then hide behind “clear and simple language” as your excuse. Step 1: State something untrue as a broadly-applicable statement of fact (“Startups who raise money are stupid and don’t understand business.”). Step 2: When people (rightfully) call you on your nonsense, just say that it’s clearly just your opinion, and that peppering your writing with “weasel words” like “most”, “usually”, “often”, and “occasionally” would just make the writing less interesting.
Now, it’s true that sometimes you don’t need to throw in weasel words. In some cases, it is unnecessary to specify that it’s your opinion, because it’s truly and obviously an opinion. But not every statement made is someone’s opinion . For example:
“In my opinion, the earth revolves around the Sun.”
“In my opinion, Barack Obama is the 44th President of the United States.”
Because some statements are clear and simple facts, it can sometimes be useful to delineate opinion from fact, especially in cases where it’s not explicitly clear which type of statement is being made. In most cases, I think that it’s pretty clear from the context that the bloggers in question are writing from their own experience and sharing their opinions, and thus littering their writing with “weasel words” would diminish the quality of the writing.
However, in many cases, writers intentionally leave out the “weasel words” not because their statements are obviously opinion, but because they know it will get people riled up and serve as good linkbait. Ironically, they often fall back to this whole idea of “of course it’s only my opinion, weasel words are bad writing, etc”, which strikes me as kind of a reverse-weasel. Write as if you’re stating absolute truth (in order to get links), even when you aren’t, and then hide behind “good writing” when people complain.
 I’m really not interested in the greater philosophical questions of whether it’s opinion that the earth revolves around the sun. If you are, be my guest, but I’m fully prepared to just accept some things as fact. The earth revolving around the sun is one of them 🙂