It’s not. That is the case. But in cases where “negligible-these-days” isn’t quite negligible enough, this still matters and unsafe + MaybeUninit is the escape hatch to accomplish it.
Safe abstractions for dealing with uninitialized memory efficiently are important in very niche scenarios to get optimal code out of the compiler and for reducing the ability to make a mistake when writing such code.
Reaching for C to do this is an emotional overreaction instead of calmly dealing with a small corner case that already has workarounds even if it does involve using unsafe