- As you point out, QM does not explain everything.
- Anything that explains everything explains nothing. Example: if God is responsible for everything, then saying "God did it" has zero explanatory power. We can't actually use the "god did it" explanation to acquire new pieces of knowledge.
That it doesn't actually explain everything is beside the point -- it explains so close to everything that "everything" is a pretty accurate approximation. In particular, quantum physics explains chemistry, and chemistry explains evolution, and evolution explains the suffering in the world.
As to your second point, you're equivocating on "explains everything". When we figure out quantum gravity and what a measurement is and any other observed phenomena QM currently might leave unexplained, and quantum physics really does explain everything, that won't make it explain nothing. That will make it
awesome for acquiring new pieces of knowledge. The sense of "explains everything" that implies "explains nothing" is the sense that refers to hypotheses that are consistent with all imaginable observations, not the sense that refers to hypotheses that distinguish the actual observations from the merely imaginable ones. The former have an explanation for all that we see, but they would still have an explanation for all that we see even if we saw something completely different. That's not QM. There are all manner of possible observations we don't see, that QM would have no explanation for if we did see them. QM is falsifiable; it's hypotheses that "explain everything" merely because they're unfalsifiable that explain nothing.