So far there is nothing saying old models are wrong. Only the mainstream dark matter hypotheses that matches all the evidence is some type of particle that is not interacting.
The difficulty is in detecting. Weakly interacting massive particles are by definition hard to detect directly.
MaCHOs, modified gravity etc. match some, never all the evidence.
It matches all the evidence because we looked at the available evidence and highly tweaked the model until it matched.
There has been no direct observation of Dark Matter, so saying "it matches all the evidence" may be redundant, since by definition, we said "Let's create something that matches all the evidence and look for it."
>It matches all the evidence because we looked at the available evidence and highly tweaked the model until it matched.
This is just wrong. This is not question of parameter tuning.
There is class of theories that include weakly interacting particles, you may tune or select model among these. But the most evidence (even newly discovered) points toward dark matter being particles because they behave like particles.
