Another use case I just thought of is upload handling for large files and reporting back the upload status. I could see that being useful. Something like that where there is a long running process that potentially needs to be backgrounded and updates could be pushed to the as client async notifications.
Did have an after thought for gaming and streaming. Those JackBox Games, like you dont know jack, are probably using streams if i had to guess. I wrote a clone of one a few years back, but i just ended up doing the easiest thing at the time, which was web sockets and storing everything in app memory as opposed to a db. The debatably good app wasn’t my finest work, but i guess i can see a use for like simple web games like this.