First, please be careful with the "experts" broad brush. Not all, and possibly not most, experts will agree on many things. Moreover, actual experts will understand that there are pros and cons that are context dependent. I would hesitate to label as "expert" anybody who categorically prefers one over the other for all cases. That's more like zealotry than expertise.
Second, for my part the biggest hurtles are in two parts. One is that at the boundaries of speed versus provable safety. At some point I don't need and can't afford the cycles added by boundary checks and other Rust guarantees, and the mechanisms provided to mitigate them are as cumbersome as writing (unprovably) safe C++ code (e.g. "const&", "std::move" and other similar constructs) compared with the equivalent Rust. The other is a more a branding problem: gratuitous maligning of C++ is problematic, and projects a sort of arrogance that I find subjectively distasteful.