Haven’t had much need for it here.

On Reddit, I use it on those things that actively take away from the conversation. Trolling, pushing obviously wrong information, blatant racism/sexism/other-ism.

But, as little as I do use it, I find it supremely important to have. Trolls get downvoted out of the conversation. It’s a way to fight brigading. It’s the only easy/consistent way to give input as to what content doesn’t fit into a particular sub. Downvoting can be problematic, but it’s less problematic than those sites that try to be all warm/fuzzy and only allow positive input.

Pretty sure FB can handle losing 10% of part of their business.

I agree that Facebook being the gatekeepers is bad. However, you’re going to need more than just “Facebook bad” to get people to use something else. The bulk of the population just doesn’t run the same calculus in regards to privacy vs convenience.