I feel like a part of that is perhaps related to 'karma farming' or posting just for up votes, which seems much more prevalent on Reddit than other forum sites with reactions. Myself I would be perfectly happy to see reactions eliminated altogether, I never liked the idea.
I agree completely. I'm an active reader and occasional contributor at Ars Technica, and the users there are so concerned with up/down votes that it creates a significant echo chamber - and I say that as someone that's generally aligned with their views. But it unfortunately creates a very homogeneous group of commentators, and I think that's a shame.