Absolutely. That's why over the last year or so I've purposefully been reminding myself to add in more "In my opinion"s and "I think"s into my posts just to drive home the fact that I'm talking about my own personal feelings and not some generalized truth.
I mean more often than not, normal forum discourse implies that most statements given are in fact meant to be interpreted as opinion without the need for "I think"s added through every post. But depending on how... strident... someone gets their opinion across, it can make the reader sometimes feel like its no longer an opinion but instead a statement of truth with the implied "And you're stupid for not knowing it!" following along behind. And that's where potential hurt feelings come into play.