What would you prefer the concept be called?
Until the point where the observations are multimodal. Then I'd be more comfortable assigning provisionally normative names. Till then it should probably explicitly reference the fact that all observations are gravitational in nature.
It needs to be "matter" in the cosmological sense [1] because of the ratio of protons and neutrons to photons produced during Big Bang nucleosythesis. We know the ratio of the number of protons to number of photons. We know the number of photons in the universe (most of them are in the CMB), and we therefore know the number of protons. That means we know the amount of "normal" matter in the universe, and it is far less than the total amount of matter in the universe (that must have survived from baryogenesis). This requires there to be "dark matter" in the universe.
The other effects like galaxy formation and stellar motion in galaxies are just things that might be caused by dark matter (though that's come into doubt).
Sean Carroll discusses it here: https://youtu.be/tZQadPmTd84?t=4642
[1] "Matter" in the cosmological sense is "stuff" that moves slower than the speed of light, as opposed to "energy" which moves at the speed of light.