"...we should start normalizing voting speech that we don't agree with..."

If we want more traffic, we should do that, as well as speech we're indifferent to. I do encourage speech to encourage traffic by encouraging user retention. I also do it because I like speech I agree with, but only rarely to encourage dissent I do not agree with. Mostly if I upvote speech I disagree with it's because I have the purpose of encouraging user retention.

Edit: upon reflection, I guess it's not that rare I upvote speech I disagree with, because I feel obligated to upvote folks I engage with, and I usually upvote people when I do express disagreement with them regarding reason, and not objectionable behaviour.