Do your feelings belong to you online?

So last night I offended a few people when I called someone out for seeking attention. I was told that if I had my own opinion or 'decisions' about it I should post elsewhere because those feeling were theirs and not mine.. but when you publicly post something online (in a discussion forum no less) doesn't that open it up to everyone else's feelings on the topic and their opinions?
Why get offended if someone's opinion doesn't match your own when you publicly put it out there for anyone to chime in on?