I think it's great that you are open minded about an alternative theory in cosmology. I argued with many mainstream scientists that dismissed all theories not in line with orthodoxy right out of hand...
PS: I am not convinced by the last plot.
I agree, it lacks quantification (although that might be because the author links herself to that study/paper and didn't provide much more details about it). But I think the point of that plot/my argument is that a model completely devoid of dark matter/energy could create something so closely resembling observed data. If I were a cosmologist, I would be intrigued by that to say the least and ask broader questions such as: are the fundamental assumptions that I am working with correct?