I don't think downvoting is a good thing. The argument is always "send a message to the user without engaging" but what you are doing is discouraging those users from posting and commenting at all.
I feel like upvoting content you agree with is a better method than downvoting content you don't agree with.
It's not used for pushing irrelevant or spammy content. It's used to show you don't agree and push that content away from sight. At least be honest about that if you support using downvotes.
People act like they are making the thread better in some way by cleaning trash. But that's not what happens. You are just making sure opinions you don't agree with are at the bottom of the thread. Nothing noble about that. Feels good, sure.