Exactly. And the well-posed gravitational theory that has MOND as a limit has not yet been found. So why is MOND considered as anything but an effective model?
Fluid dynamics is not a fundamental theory, but an effective model, as you said. The point here is that MOND can't explain something that GR has been able to explain for 100 years (precession of Mercury). So any serious gravitational theory needs to at least that for serious consideration.
If you're claiming that dark matter is superior because it is a fundamental theory, I fail to see why a fundamental theory that's empirically wrong is supposed to be better than an effective model. Rather than propping up dark matter, astrophysicists should be focusing on novel ideas that reproduce MOND, like superfluid dark matter, or at GR modifications in the MOND regime.
I never mentioned dark matter. My only point is that any modern gravitational theory needs to do at least as well as general relativity. That means (among others): explaining the precession or Mercury; describe black holes; predict gravitational waves. So if MOND is to be taken seriously, it needs to do all of that. That's all, really.
That's a really bad bar, beacuse it creates a bootstrapping problem: There's a lot of very difficult math that you have to do to get to that point.
And if you say "don't take it seriously until it explains all those things" then why should anyone bother to do the heavy lifting for all that math?
Let me make a different suggestion: As soon as you have one or two very interesting observations that modern GR can't explain that are apparently gravitational, then you should start encouraging people to take it seriously and start working on the hard math.