The ideas are similar, but transducers all greater flexibility and composability and testability. The pure idea of "pipelines" isn't anything new, though, as you pointed out.

When you have a Unix pipeline, let's say "cat file | grep -v '^#' | sed 's/\/t//' | wc -l", or something, each step must specify where the input and output comes from. i.e., you can't "pull out" the grep, sed, and wc parts, and then tell it that it's coming from a network socket, or web service instead. It _must_ come from a file descriptor (stdin, stdout). And you can't (easily) multi-thread just the sed piece. Or (easily) add a logger between cat and grep. Or a retry between two parts. Or have it read from a network socket instead. And it's not simple to combine these pipelines with other complex pipelines.

Anyway, take that concept, run with it for a while, and you get transducers.