In fact, we can see this "defaults matter" problem in Rust as well. Note that Rust by-default assumes that code is running in a context where a dynamic allocator is available, but allows one to opt-out of this ("no_std" mode). Code written for embedded devices or baremetal contexts uniformly opt into this mode, but because it's not the default, you can't just pull any old library off the shelf and expect it to work for you, so the ecosystem is much smaller and less mature. Defaults matter.
The argument is often about when ownership and borrowing is truly necessary. Rust has its uses, but arguably not all the time and with everything, because of its defaults.
It opens up entirely new avenues for statically error-free programming, letting you model things like “if the caller has an instance of this type, I can guarantee that this other larger proposition is true”. Namely without also having to handle the case where the user smuggled another instance from another call site.
This is really, really useful.
Isn't the crux that Rust does those things without a garbage collector, that's the novel part? Someone correct me if I'm wrong (likely), but I think all those languages have garbage collectors, which Rust doesn't.
The thing about it being optional in some languages is that it's an experiment, but one that as a feature it really pays off the more code in the ecosystem is compliant to ownership tracking. For rust, it's the vast majority of it (with opt out explicitly findable..) For languages offering it optionally, it's harder to assemble the full benefit.
That's not quite how it works in various languages. You appear to be thinking of the garbage collector as something inseparable from the language.
Both Dlang and Vlang have optional garbage collectors, that can be turned off. In the case of Vlang, none of its libraries depend on the garbage collector. Vlang offers optional (flexible) memory management, somewhat similar to Nim (but they presently don't have optional ownership).
In the case of Julia and Vlang, their optional ownership is new and experimental. Dlang's optional ownership has been around for some years now, showing that it could be done.
Dlang and Vlang allow you to choose the type of memory management (along with some other languages) that you would like to use. Vlang does it by command line flags. You can turn off garbage collection and turn on ownership.
Until you need a library that was written with the assumption of using a garbage collector.
If you were to implement a Rust GC, then Rust can guarantee that references haven't escaped the current thread, which means there is no stop the world pause anymore, only the current thread gets paused, which is acceptable.
In various forms, affine types, linear types, dependent types, effects, formal proofs.
The list is already rather long, D, Chapel, Swift, Linear Haskell, Ox, OCaml, Koka, Ada/SPARK, Mojo,...