Neutrinos don't interact via the strong force, actually.

Most proposals for new dark matter particles extend the Standard Model in one way or another, rather than simply ignoring it. The fact is that no particle we understand today has the necessary properties to produce the evidence that we have. Skepticism about any specific proposed particle is still valid, because there haven't been direct detections yet, but skepticism about the necessity of some new particle is no longer warranted.



No, large undetected mass would not explain acceleration, because the gravitation of matter is attractive. Dark energy causes a repulsive gravity-like force, which leads to acceleration. At this point, the leading idea is that dark energy is due to the cosmological constant, a perfectly allowed term in Einstein's field equations. The main question is why the cosmological constant has the value that we measure experimentally.



Neutrinos are dark matter, but that doesn't mean that they come anywhere close to accounting for all of the dark matter that we observe. I don't understand this distinction you make between "relatives of the neutrino" and "mysterious theoretical dark matter." A new particle is a new particle.

Also, you might note the history of neutrinos themselves: the neutrino was first posited to explain particle decays which seemed to be missing some energy in the decay products. It wasn't detected directly until a decade afterward. Sounds like a familiar scenario, doesn't it?



Why exactly do references to particle physics set off alarm bells for you? Particle physics is a huge success story of going from prediction to detection; it happens over and over again in the history of the field.

If your prediction is that the gold is two miles underground, and you don't see any after digging only one mile down, that's no reason to give up. You knew that you probably wouldn't see any after only a mile, but you still had to dig that first mile in order to be able to dig the second mile.