A big problem of the modern cosmology is not only that we have observations that do not fit models but that we do not know if the observed discrepancies are the real problems with the models or are artifacts of calculations.
For example, to simulate a galaxy one should use a model based on General Relativity. But mathematics behind GR is too complex to allow simulations on the scale of the galaxy even with all that modern computation power. So instead of GR the calculations use Newtonian mechanics with minimal corrections for the light speed limit. Plus there are a lot of other simplifications like replacing star systems with hard balls that reflects when hit each other with no notion of matter transfer or ejection in the process.
Then we see that the simulation does not fit data. A typical explanation that is used is that of dark matter hypothesis. But this is unjustified.
We have no proof that numerical simplifications are mathematically valid and do not lead to a big error on a galactic scale. Moreover, there were recent papers that tried to account at least for some effect of General Relativity. Apparently it was enough to explain at least some effects previously attributed to the dark matter.
So it can be that the dark matter is just an artifact of inaccurate simulations.
Not a cosmologist, so I'll defer to any simulators who are more up-to-date with the field than I am, but the papers linked from wikipedia are about the fitting of models to existing data, and by using a more complete model, they can better constrain values in the models; whereas the massive 3D simulations are looking at a different problem, and go through a rigorous level of validation and cross-checking, with different microphysics tested and examined. Both dark matter and dark energy fall out of GR—they can both be zero, but they can also be non-zero.
For example, to simulate a galaxy one should use a model based on General Relativity. But mathematics behind GR is too complex to allow simulations on the scale of the galaxy even with all that modern computation power. So instead of GR the calculations use Newtonian mechanics with minimal corrections for the light speed limit. Plus there are a lot of other simplifications like replacing star systems with hard balls that reflects when hit each other with no notion of matter transfer or ejection in the process.
Then we see that the simulation does not fit data. A typical explanation that is used is that of dark matter hypothesis. But this is unjustified.
We have no proof that numerical simplifications are mathematically valid and do not lead to a big error on a galactic scale. Moreover, there were recent papers that tried to account at least for some effect of General Relativity. Apparently it was enough to explain at least some effects previously attributed to the dark matter.
So it can be that the dark matter is just an artifact of inaccurate simulations.