I tend towards skepticism about the whole positive thinking thing - despite having suffered depression most of my life, and it's still there, lurking much more insidiously (imho) in me than even my alcohol addiction.
The middle way seems to me a lot more helpful these days. So I actively seek out readings / reflections on just that. A recent example which totally resonated for me is 'The Antidote: Happiness for people who can't stand positive thinking.'
The Antidote by Oliver Burkeman - review | Books | The Guardian
So, yeah, re the SR posts of evident suffering, I try to remind myself of where I've been in that regard, and where I can go, any day or moment, if I allow that mental suffering to overwhelm me. It's simply where those souls Just Are, right now, when they post. Gentle listening and encouragement from afar is often all people are asking for.