> So their proposal is a superior primitive.
This lines up with my thinking. The proposal should give us a building block in the form of the primitive. I would expect the grandparent comment’s API to be provided in a library built on top of a language level primitive.
How would you then deal with a stream of UTF8 code points? They won't fit in a UInt8Array. There will be too many for async iterators to perform well: you'll hit the promise thrashing issues discussed in the blog post