>It is also entirely possible that Dark Matter and Energy don't actually exist.
Exactly. The whole basis for belief in "dark matter" and "dark energy" is basically: "our theories on how the universe works don't compute, so there must be some invisible things (dark matter & energy) we cannot detect since our theories can't be wrong."
Except for the slight problem that observations of the bullet cluster show gravitational lensing inconsistent with the observed mass of physical matter. MOND has no explanation for this.
No our theories were wrong, that was obvious, dark matter and dark energy are (part of) the new theory
We're going with them because all the other new theories end up requiring fractional dimensions or some similarly bizarre space time and still don't end up explaining things as well as "I dunno guys maybe there's just some stuff we can't see". We already know there's a bunch of stuff we can't see, dark matter is just some other kind of stuff we can't see. Dark matter is on the correct side of the razor.
The shift here is that dark matter is detected only in aggregate. And massive aggregates at that. What are the properties of dark matter? Where does it come from? How does it interact with other matter, light or dark? No idea, because it's only detected as a correction term.
Exactly. The whole basis for belief in "dark matter" and "dark energy" is basically: "our theories on how the universe works don't compute, so there must be some invisible things (dark matter & energy) we cannot detect since our theories can't be wrong."