This is also a problem with Rust conversations and tutorials online: There's a lot of talk about what not to do or what you can't do in Rust, but it's rarely followed up with an explanation of what users should do.

Mutexes aren't an entirely foreign concept to many programmers. Obviously if someone can architect their system in a way that doesn't require Arc<Mutex<_>> then go for it, but we need to be careful about giving blanket advice without alternatives.