Yes, that's the general idea of individual dark matter theories. We have an enormously successful cosmological model, lambda CDM, that includes cold, weakly interacting matter. Many theories have been put forth to explain what the additional matter actually is. A few of them are actually not created originally to account for the matter in lambda CDM, such as axioms. But yes, there correct, it's the lambda CDM model making successful predictions, the individually dark matter theories are just along for the ride.

Anyway, you are free to spend as much or as little time as you like considering different speculative theories by whatever metric you see fit. I find it odd that you are a proponent of MOND theories but seem to dislike theories that modify existing frameworks and are continually refined to match observational data.

Au contraire, I am seeking precisely theories that actually modify existing frameworks without merely begging the question. The approach of "oh, must just be more matter but it's weird that we can't see it" is going to be seen as ether or geocentrism is now. It's just grossly unimaginative and ironically doesn't actually modify existing modes of thinking, i.e., assumes that gravity is still a fundamental force if only we could describe it as a quantum field.

MOND is a change to the existing framework that makes predictions from the basis of a theory that actually explains the data "discrepancies" we're seeing vs typical assumptions. The discrepancies are testable with MOND. It's not merely a post-hoc justification of some detailed maps of where matter "isn't". While with dark matter all one can try to do is detect particles that we are already blindly assuming are there. Dark matter enthusiasts love to espouse the "shoulders of giants" thing with their tiny incremental modification to LCDM but they're taking an approach that fails to learn from the historical blunders of physicists before who wanted to assume some substance exists and then try to back-prove its existence with increasingly elaborate and specialized theories of origin.