There’s some of that going on, yes. And there’s the fact that the board has become more left-leaning over time (I think that process really got going after the Iraq war started) and there’s now a Democrat in the White House, and a lot of Dopers support him strongly overall.
Like I’ve said in other threads, this is an issue I’m interested in from a moderating standpoint. Hardcore partisanship bores me. I realize people are entitled to butt heads if they want to but I’d rather read a nuanced discussion of a complicated issue than watch people joust. When I see off-topic broadsides about one party or another I try to moderate that and keep the discussions on topic, but at a certain level, if people want to post that kind of thing, that’s what the forum is going to be. But I’d like to nudge it in a different direction to whatever degree is possible.