I think bevy is a much more ambitious 'total' framework for making games. Plus, I think by its nature Rust forces you to deal with the really hard questions up front, and get them right first time. In C++ you can punt some of these questions and build a less-than-perfect architecture more quickly. Please don't think I'm disparaging C++, I develop in it for my day job. But I do think there are different trade-offs at different stages of a project's lifetime.