I think most take umbrage with the false equivalencies. To say "they all do it" and leaving it at that gives the impression that you feel there is no measurable difference between any of the media outlets or politicians. When people are pointing out the egregious behavior of certain examples, you tend to fall back to a defensive position of "hey guys I am just offering my own opinion" without actually mustering an actual legitimate logical argument regarding how that one position has a counter example.
Now I am not going to try and say I haven't done the same thing, as I have been known to drop some drive by snark now and then. But to expect that just leaving "comments" and when people challenge you on them, labeling them as unwilling to change their mindset, is disingenuous. You are essentially making a statement, without proof, and when challenged upon that statement, falling back to the position that it is just an opinion and people need to be more open minded.
I'll debate anything with anyone, as I love sharpening my arguments. If I don't expose myself to as many ideas as possible, I am doing myself a disservice. If you ever want to discuss things, I would be glad to, but I don't want to spend my time trying to make a cogent argument only to have it dismissed because it doesn't jive with your world view which in turn makes me the one afraid to move away from my comfort zone.