If your goal is to converge on correctly functioning software, you know, for the benefit of the users of it, then fail-fast can help.
If your goal is to optimize the sleep patterns of devops people and make changes to code without testing before releasing it to production, yeah... do what you need to do. :)
You can have correctly-functioning software when parts of it are operating in a weird way. The complaint I have heard about Rust crashes is that the default behavior is to crash in any situation that could possibly be weird.
By the way, the trade you're talking about is great for desktop software (especially for browsers), but server-side software at scale is a bit different.
The borrow checker and all the Rust safety stuff is also completely orthogonal to most forms of testing. You don't get to do any less because your language protects you against a specific class of memory-related errors.
