That's probably fine somewhere like HN, but I'd warn people against doing it too much IRL. I have an ex-friend who liked to play the "you just need to" game as a primary learning technique. I say ex-friend because I got tired of the initial implication that his few minutes' of thought could overturn lessons it might have taken me years to learn, until I did the labor of educating him. Maybe some of that was a "me thing" except that he has several other ex-friends for the same reason. I have other still-friends who are a bit less extreme about it, but it's generally not a relationship-positive behavior.
I don't think there's anything wrong with qualifying your opinions. You can still get people to challenge you on them. Isn't that why people start their sentences with "for sake of argument" or "playing devils advocate"?
Sometimes stating an opinion is making the unconscious, conscious, and then learning the truth about a subject by the insights and replies of others.
In other words, I'm shooting in the dark most of the time on HN and waiting to hit a target, or some truth I can salvage from the replies of others.