Breeding seeds is a bit different. Those genetic mutations that do exist in seeds are brought out and are subtle. Too much mutation could cause a species to wipe itself out. So the strongest qualities are usually selected over the mutations. (A form of natural selection)
Genetic mutations are usually small in plants, in fact most of the time we don’t even realize them. But every time you clone a clone, you add a bit more mutated qualities on top of what already existed. So over generations of the same clone, the likelihood of that current plant being exactly like the original donor gets smaller and smaller with each generation.
But in short yes, feminized or not...mothers can produce sub-par results after many years of cloning.
Also, some people don’t realize the roots need to be trimmed once or twice per year. This can also contribute to people getting rid of their mothers.