People need to learn the difference between "fact" and "opinion". Way too often they try to deny facts by saying "hey, it's just my opinion!" No, it is not opinion, it is ignorance.
@ooBrony - it really depends on what that opinion is. Saying that "in my opinion homosexuality is a sickness" isn't an opinion at all as it was denied to be a sickness by therapists long ago. And this is what tickled me off this time.
I hear people protecting some really big nonsense with "it's my opinion" as argument, we should start telling such geniuses where opinion ends and stupidity begins.