The basic problem with uninitialized buffers is that they effectively require write-only references to exist, and Rust's type system doesn't have (and doesn't easily support) write-only references, only read-only and read-write. MaybeUninit is a partial solution to the problem, but since it's a library solution and not a language solution, it suffers from a lack of integration with the language, e.g., getting MaybeUninit fields from a MaybeUninit struct is challenging.

And the most aggravating part of all of this is that the most common use case for uninitialized memory (the scenario being talked about both in the article here and the discussion you quote) is actually pretty easy to have a reasonable, safe abstraction for, so the fact that the current options requires both use of unsafe code and also potentially faulty duplication of value calculations doesn't make for a fun experience. (Also, the I/O traits predate MaybeUninit, which means the most common place to want to work with uninitialized memory is one where you can't do it properly.)