There's definitely a cost in terms of features BigCo doesn't need that get deprioritized. But that work still gets done if other people need it, it's just slower, and I don't think you could ever pull off making things worse on purpose in a big community run project like Rust.

The only times this actually happened are C++ and CORBA as far as I remember. Both of them were bureaucratic design by committee efforts from the start, the people doing it weren't users but implementors looking to stop competition, and it all happened before the open source era.