* Languages with comprehensive support for affine types, but that are otherwise too limited to be really useful for general purpose programming. Usually this is due to a lack of industry support.
* Languages with bolted on support for affine types where you can't get consistent performance benefits out of code written in that style and it's very difficult to write and compose code written in that style.
* Complex languages with advanced type systems that can emulate affine types, and are extremely powerful, but are borderline unusable for any purpose.
Like I said, whichever of those three language categories you're thinking of, my reasoning applies. No mind reading necessary! I understand though that you believe safe concurrency has been solved since Modula 3 because you can just lock every object while it's in use (why didn't anyone else think of that?), so maybe you don't really appreciate the vast gulf in usability between affine types in these kinds of languages and in Rust.