atm did not have cell delivery guarantees. it did have per-connection qos negotiation that could include the loss probability as one of the many metrics that were supported. the only way to provide 'zero loss' is to implement hop-by-hop error detection and retransmission, which is only really done in HPC networks, and some satellite transport schemes where the loss is high and bursty and the latency is high.

however, actually building a functional routing infrastructure that supported QOS was pretty intractable. that was one of several nails in ATMs coffin (I worked a little on the PNNI routing proposal).

edit: I should have admitted that yes, loss does have a relationship to queue depth, but that doesn't result in infinite queues here. it does mean that we have to know the link delay and the target bandwidth and have per-flow queue accounting, which isn't a whole lot better really. some work was done with statistical queue methods that had simpler hardware controllers - but the whole thing was indeed a mess.