Releasing a dirty stream to the D/A increases its processing
No it doesn’t, latency has nothing to do with it and buffers are never “underutilized” because of back signaling.
Perhaps example will help:
Worker (DAC) has to place items on conveyer belt (D/A Converter) of some machine in exactly one second spacing, but another worker (computer) hands them too slow or too fast creating uneven space between them. Remedy for that would be shelf with many items on it (buffer). One worker adds bunch of them (frame) to the shelf every so often and the other places items on conveyer belt in even intervals, yelling back “get more (or less) next time” to keep decent amount of them on the shelf (back signaling).