[remram]

> The queue gets full and stops accepting input, and the prior machines stop sending input as a result

That is backpressure...

Interestingly I think if Factorio didn't have backpressure, and unconsumed items disappeared when they reached the end of the conveyor, the game would be easier because you could just put every kind of items on a single belt. Un-balanced consumption wouldn't stop down the next production stage because the conveyor would keep running, whereas now if you're not consuming one type of item from a mixed stream you will block it preventing you from getting the other types of items.