No, it's precisely true.
I've seen a lot of people (maybe a lot of your prior burners?) make similar complaints as yours, and without exception, they were all right-wingers pushing absolute fucking nonsense, and whining that the rest of the forum community wouldn't swallow their bullshit propaganda unthinkingly, like good little sheep.
Even your own example; if you're citing a known propagandist or hateful source, yeah, people aren't going to give it the time of day. Because they have looked at enough content from that source to know how dishonest and abusive that content is, as is the motivation behind producing it. They aren't dismissing it because of what side it's on; they're dismissing it for its history of abusive and/or dishonest conduct.
Sure, right-wingers try and pretend this is about partisanship, but it is not. It's about facts, and truth, and reason, fundamentally. If your arguments and sources won't live up to that, they're gonna get pulled apart and mocked, because they deserve to be so treated.