I think reddit is the single largest source of player feedback, but it's not the "main" one because that implies that it's the only one that matters. The CM team gather information from every source we have available to us. Even Facebook.
I think there's a bit of a misconception about polls as being somehow sort of "morally authoritative" in a way that alludes to direct democracy. Participation in polls is historically pretty low, and while I don't think that makes them invalid (if you want to vote you can vote) it doesn't make them especially informative if what we want is the best understanding we can get of what our players really want for the game. I don't mean polls are bad, and they do serve a purpose that we should make better use of, but they're "inaccurate" in much the same way reddit is.
(There's a complex tangent there on how difficult that question is to answer even in theory - for example, to what extent should currently inactive players be taken into account? We can, and should, prioritise the needs of currently playing players, but a lot of the time when we're trying to improve the game we're also hoping to win back players who may have lapsed over the very thing we're fixing. A similar example that comes up a lot is the idea of limiting polls to certain audiences - players often propose that only ironmen be allowed to vote on ironman matters, only people with high PVM achievements be allowed to vote on endgame PVM matters, etc.)
I can't see an obvious path to a situation where something like nerfs are polled. I'm not involved in every decision that gets made, but I think most of my colleagues would espouse a similar methodology in that it's always a combination of factors. It's important for us to understand aggregate player opinion in a fairly vague overall "is this going down well?" sense, but also to pay attention to the dissenting opinions on that. We then take that overall vibe, combine it with more individual, specific feedback (which can come from reddit and also multiple discords) and then process it internally, where we need to take into account other factors like dev time, tech issues, upcoming projects, and myriad other factors.
For example we often ask for "community hitlist" requests for changes, and reddit provides that to us in a handy prioritised format. However, we can't just take the list in order of upvotes and treat that as our priority list - we have to take into account all those other factors when we're trying to figure out which to work on.
The way I usually phrase it internally is that we can't just do whatever reddit demands, but at the same time we do need to listen to what our players are saying and weight it very heavily. Reddit is great for highlighting areas of concern in a very public forum, while at the same time containing a huge quantity of nuanced opinion on the topic all packaged in one place. The discussion doesn't stop there, but it is a great place to start.
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