I built a fairly complex backend directly on top of Hyper[0] (it doesn't even involve that much glue, really) in 2016 and have updated it as Rust and Hyper have matured. It's actually a delight to work on, and I brought a new hire on board recently who had no trouble getting up to speed, since everything is just straightforward, idiomatic Rust.
I've looked at basically every Rust "web framework" that's been released since 2016, and I can't see any of them simplifying the codebase enough to justify using them. Quite a few of these frameworks result in code that isn't obvious to a Rust programmer who hasn't used that framework before, too, which I consider a disadvantage (I prefer obvious over clever).
[0] edited to add for those that may not be aware: Hyper is a client & server HTTP library. Many/most of the frameworks are built on top of it.