What's sad about it is that SO was yet another place for humans to interact that is now dead.

Whatever. I haven't seen a graph like that since Uber kicked the taxi industry in the yarbles. The taxi cartels had it coming, and so does SO. That sort of decline simply doesn't happen to companies that are doing a good job serving their customers.

(As for forums, are you sure they're gone? All of the ones I've participated in for many years are still online and still pretty healthy, all things considered.)

I’m sad SO died, even if they deserved it.