If PA was actually capable of half of what JACK does, they would be fine with it. These people just needs to record music without latency. But PA does not do what they need, so they would indeed complain.
I think what zlynx is saying is that even if PulseAudio emulated JACK, and did 100% of what people use in JACK, exactly as well or better than JACK did it, people would find something to complain about. Maybe they'd complain that PulseAudio is "bloated", or that this is yet another Poettering monolith.
FWIW I've been able to get similar input latency with PulseAudio as with JACK, that's not so much the issue as synchronization. If PulseAudio introduced a timecode like JACK, that'd probably be close to enough.
If you were really just going for minimum latency, your recording application would use ALSA directly.
This is not too difficult in PulseAudio. Every output has a "monitor" which can be routed to any application that's recording. You can do this through a GUI called pavucontrol, though it's not as pretty or flexible-looking as patchage or many of the other JACK patchbays. PulseAudio is, of course, more geared toward consumer and basic professional scenarios in general. Synchronization becomes important once you're routing through a couple of different applications.
FWIW I've been able to get similar input latency with PulseAudio as with JACK, that's not so much the issue as synchronization. If PulseAudio introduced a timecode like JACK, that'd probably be close to enough.
If you were really just going for minimum latency, your recording application would use ALSA directly.