You certainly do hear creepy stories about hosts surprising guests by only having one bed. And more than that. Of course, if everything is mutually agreed then that's fine.
I was actually pretty surprised when I was speaking to another couchsurfing host how many women he'd hosted that he'd slept with. Perhaps I'm (or was) naive but it never occurred to me that people would use it for hooking up.
We never received any negative feedback and were in high demand. Aside from that one super busy weekend, where things did get a bit cramped (but people knew in advance that it would be), nobody shared any beds or couches and couchsurfers had rooms separate from the hosts. I wouldn’t have had it any other way. Sharing beds with the host is... creepy (unless the person was given their own bed/couch and they mutually decided they wanted to share a bed, of course).
I miss couchsurfing too. I stopped being part of it around the time it got a sense for being a bit commercial. My circle of couchsurfing friends did it for the cultural exchange and at some point it drifted from that to just free accommodation and drinking parties. At least that’s the sense I got.