This is how I view that comparison: I go to a restaurant and don't like the food I get. Afterwards I do not shout about how much it sucks, but I write into their guestbook (in a short and calm sentence mind you) that I don't agree with the 100 people before me concerning the food quality. I will certainly not get badmouthed and pitchforked by those 100 other guests and the manager will certainly not ask me to leave. Heck, if it's a decent restaurant, he will even try to make up for it and bring me something else or at least ask what exactly I disliked about my dish. But this is the internet, and it overflows with intolerant and subjective people that will use their collective power to deny an opinion that doesn't fit their own.

I also wasn't surprised about this reaction in the least, as you claimed. I absolutely expected it. Doesn't mean I have to stay silent towards such a generalized, glorifying statement though. I see no rule saying "You are only allowed to post positive feedback to any thread." and I sure am glad about that.