It's got the same vibe as going into a circle of people having fun and telling them they're trying too hard. What's the effect you're going for?
You're not being stopped from having an opinion - your comment is visible - but sharing one that'll only serve to bring down people's moods makes everything a little bit worse I think.
If you're in a circle of people whose moods can be brought down because of a shared opinion, you're in a circle of prepubescent children who haven't learned to regulate their emotions like a grown up.