> Were I actually at risk of self-harm, I struggle to imagine how socially isolating me is a proper response.
I'm going to put on my cynical hat here, but I think you have a perfectly reasonable expectation. Human communities evolved in such a way that everyone knew everyone. If one person got sick, then the community was just as concerned for the individual as they were for risk it posed to the community.
Now, I'm not sure how it came to pass that giant tech companies like Facebook got landed with the responsibility of community shepherding and management (rather than being telecommunications carriers) but it's not a role Facebook should be doing, because at that scale, the people who are unhealthy are going to be treated like a defective unit, which needs to be pulled out of service and replaced, so the machine as a whole can keep humming.
Simple fact is that Facebook is a website, and a website can't care about you or anyone else for that matter, because it's just a website. But now that we're all socially subordinated to a website that controls the means by which we communicate with friends, family, and loved ones, I think we're going to see a lot more of this sort of lack of compassion becoming endemic to humanity.