Because being user-friendly is way, way, way more important than things like privacy, not being bombarded by ads,
People gravitate to the technology that they can use.
I live in a small town. Every business and service has a Facebook group because it’s usable. A couple of stalwarts maintain web pages but they’re full of inaccurate information because they’re too hard to update. The Facebook groups, on the other hand, are constantly up-to-date, and the owners are quick to respond to any comment on them.
That’s before you get to network effects. Everyone in the town uses Facebook. So when kids ask for a messaging or social media account, they ask for a Facebook product so they can talk to their friends and family.
It’s incredibly shitty. Everyone in town would agree with your sentiment, but they bounce off competing products. The effort involved in hosting a service isn’t a higher perceived cost than the ads, privacy invasion, etc.
Listening is indirect help, passive help. It’s helping simply by existing
Not in my experience. The listener is helping the speaker organize their thoughts, work through their feelings, and (in some cases) decide on a course of action. The listener needs to ask questions, understand the speaker, and help them sort things out.
In a spouse or friend situation, the listener is probably also providing emotional support. Which can be immensely helpful, since it validates the speaker.
There’s also follow up. The listener should talk to the speaker and see how their feelings have evolved.
I self hosted a blog for a while. Tweaking it was fun, but eventually the novelty wore off. If I ever do it again, I’d probably use something hosted so I spend more time on the content instead of the back end.