The point is not hosting, but to monetize the Rolling Stone's brand reputation. They have a well-known and somewhat trusted brand (although less trusted than it once was [0]). They're allowing "thought leaders"—aka PR flacks—to leverage their brand to publicize marketing and personal branding content. Forbes does the same.
Presumably they are cashing in on their name so you’ll get more exposure to your idea if you publish on Rolling Stone vs Medium. So what they are selling you is eyeballs and legitimacy for content & money. Makes sense.
It’s a shame because I grew up reading Spin & Rolling Stone and they have become unsustainable and now irrelevant empty shells of themselves.
[0]: https://www.nytimes.com/2015/04/06/business/media/rolling-st...