I think you're ascribing a bit too much to materialism, and then arguing against the improper ascriptions.

Materialism simply posits that the material, not the mental, is ontologically prior. You can then go check and find that, indeed, it seems to be so, in that the material supervenes in myriad ways upon the mental (c.f. mescaline, alcohol, nitrous oxide, ether, low blood glucose, raising your body temperature to 35C, etc. etc. etc.) and not vice versa (I cannot change the speed of light by thinking about it).

You might be greatly displeased that psilocybin's binding to your serotonin receptors will cause all manner of unusual subjective experiences that are unrelated to anything external (and that aspects of the experience can be enhanced or blocked by more selective drugs that target serotonin receptor subtypes), or that you do not gain qualia experienced by water that you drink, but that you are so put out is no more germane than is a baby's frustration that they cannot both chew on their hand and drink from their bottle at the same time.

When it comes to giving detailed predictive models that achieve a good degree of cognitive success, materialism has indeed "explained" lots and lots of things. If that doesn't count for you, well, maybe you have the wrong idea of what "explained" should mean.

(Notwithstanding that various flavors of idealism also have explained nothing, if held to the same unreasonably high standard.)