Thinking about eliminating bufferbloat was the original line of thinking that made me think of LIFO queues, since the latency properties of a drop-oldest LIFO queue are (I think) only related to the burstiness of the traffic flow, not the volume, and so steady flow cannot ever cause any intermediate node to hold a persistently large queue of messages that will ever be transmitted.
From the perspective of an application transmitting over the network, a steady flow through a saturated link results in packet loss but not latency, while a bursty flow results in small burst-sized latencies to random packets, and some reordering as a result. Because the _downstream_ traffic from one saturated link is typically not very bursty when it hits the next saturated link, negative effects won't accumulate in the same way that latency does in bufferbloat.
Kind of. Using 'adaptive lifo' with a variant of CoDel is something Facebook explained they do address tail latency:
Most services process queues in FIFO (first-in first-out) order. During periods of high queuing, however, the first-in request has often been sitting around for so long that the user may have aborted the action that generated the request. Processing the first-in request first expends resources on a request that is less likely to benefit a user than a request that has just arrived. Our services process requests using adaptive LIFO. During normal operating conditions, requests are processed in FIFO order, but when a queue is starting to form, the server switches to LIFO mode. Adaptive LIFO and CoDel play nicely together... CoDel sets short timeouts, preventing long queues from building up, and adaptive LIFO places new requests at the front of the queue, maximizing the chance that they will meet the deadline set by CoDel.
Fail at Scale (2015), https://queue.acm.org/detail.cfm?id=2839461
From a networking point of view, (tcp) bufferbloat across hops is a more complicated problem. Ref this exchange between u/jorangreef and others: https://news.ycombinator.com/item?id=10546651