We once hired a very smart fellow to build out a media processing pipeline. He did with rxjs, but it wasn't scaling well. We tried to get with the paradigm for a bit and help scale it up, but flame graphs in profiler output were all crazy, and it was a pain to wire in timing traces, etc. We built a POC imperative version just to prove that we could indeed achieve the throughput we thought we could, and then we just said, well hey, this is faster and simpler, so... let's just go with this instead. And so we did.