As someone who has repeatedly been pulled back to this specific brand of content when bored, my understanding is it takes advantage of a need for companionship. It hacks into that human instinct while accompanied by motifs that are already familiar (knowledge of foreign culture, moé art styles, openness to sending coded signals about sexuality) instead of featuring video feeds of real people that may push away the socially anxious. The value add appears to be: Now you "know" a girl who knows about the exact things you do and does not shy away from making targeted innuendos from the outset (unlike any average person who would be creeped out, going by society's rules for real life interactions), validating the pent-up feelings that the target audience would usually just blow off, and whose level of physical attraction is not predetermined by nature but is instead designed by an artist to surpass nature.

Most importantly, nothing is scripted or predetermined (or it at least feels that way), and they regularly acknowledge that the people making up the audience exist, in real time. "You guys." It's difficult to feel the same empathy when you're just watching a television show.

There are some signals they send to tone down the intimacy of the experience. The model is designed and rigged by artists, who sometimes have their own channels and are frequently welcomed and thanked, to make the experience feel like the product of hard work and creativity instead of stardom and charisma alone. Much of the entertainment value (and the only real reason I continue to care) comes from the interactions between the streamers themselves rather than with their audience, which are highlighted for posterity and endlessly remixed. There have been enough times where five minutes after dropping into an arbitrary stream something interesting would happen as a result of the streamer's behavior or circumstances, and only a few hours later the fanbase would post the highlight. Some of them end up with hundreds of thousands of views after a few weeks.

Additionally, in my mind the thing they did better was to not try to "act" as much, which would make the experience feel fake, much the same as just watching television where nobody is attempting to speak to you directly. It's the supposed sense of "authentic human interaction" packaged in the 2D format which is the major innovation over the static things from decades past like comics, and which was only possible to have with the ease of livestreaming and real-time comment feeds.

For me at least, the most interesting parts are actually when the streamers are "doing nothing" - sitting around talking about things, playing video games together - in just the same way as someone in real life might do with their friends every Friday evening, except the friends are guaranteed to be attractive and interesting to listen to. It is designed to be close enough to the "basically nothing" you'd expect from interacting with actual friends to de-stress (unless you set your friends to that high a standard), or being invited to a party where all you have to do is listen to other, more interesting people's anecdotes and laughter to feel as if you're a part of something.

I'd been to several of those parties and gatherings many times in my adolescence, where I felt something by just surrounding myself with people having a good time and feeling no pressure to be a part of it. I sometimes wished those moments would never have to end and the people that made them up didn't have class to go to at 8 in the morning the next day or other obligations that would prevent them from getting back together in a room any time soon.

This is the commercialization of those after-school hangouts, seven days a week.

At times it feels like the genre has obsoleted large swathes of content if done properly. People who watch television shows with a predetermined outcome no longer have to make up their own idea of attraction when someone playing a 2D character can actually respond in real-time to real (but faceless) people. I'd given up a few things I used to follow in the past which I'd realized were just trying to fill the same void that the streamers did, and the streamers filled the void that much better. No, this isn't the most healthy thing to admit.

But I make it very clear to myself that none of these people will ever know or care about who I am as an individual. The streamers essentially carry the weight of tens of thousands of people they will never know in an attempt to satisfy them all for the company's benefit. They're entertainers. But there are many people for whom that is not the case and the attachment becomes (a higher level of) parasocial. None of us can deny that the temptation is a lucrative one for the agencies that succeed.

Also, there is not an insignificant subset of people outside of YouTube who find the idea of paying money for call-outs to be "cringe", and I completely agree, but nobody on the business side has any incentive to stop them. Many people want to send money thinking all of it will go to their favorite streamer (which is decidedly not the case, given it goes through both the agency and YouTube). Also, the official chat feeds are militantly patrolled to prevent defamatory remarks from showing up on-stream (or even comments about unrelated streamers), so there will always be a subset of opinions that will never be discussed there.