It's really old code that I think the devs are scared to touch in case they break something. It uses floating point numbers, so you can never fully utilise a pipe, it'll be 599.999pm instead of 600pm. You can't keep the fluid flowing because it takes it in chunks.
I had multiple factories working fine, but after many many hours of it slowly being 0.00001 off somewhere due to a rounding error, it stopped working and brought many lines to a halt.
It needs updating really badly. But I just think the devs are content with how it is now and don't want to risk breaking things more than they already are. Which is unfortunate. I mean if they release a DLC, I really hope they tackle all the issues first.