“binary” is not necessarily a benefit, particularly for developer tooling/debugging
Streaming is one area it may have a benefit but honestly the other issues outweigh that possible benefit (and it’s not like there aren’t other ways to stream data to a browser without resorting to polling)
It's not just streaming. Any heavy natively binary objects (think scientific computing) are a pain to marshal without a good binary interface, and it can easily become a real performance issue.
“binary” is not necessarily a benefit, particularly for developer tooling/debugging
Streaming is one area it may have a benefit but honestly the other issues outweigh that possible benefit (and it’s not like there aren’t other ways to stream data to a browser without resorting to polling)