Agree that it would have impact, but not the good kind.

The services that deal with CSAM would be flooded with false positives from the automated scanning. They would, in turn, have to find methods of short-cutting the assessment of these false positives so that they can actually function.

The real CSAM would be drowned out by family snaps of kids in pools, of teenagers sexting each other, etc. The ability of the relevant services to actually detect and catch real abusers would be severely hampered. Actual abuse would be caught less and more kids would be harmed.

Five minutes of thought leads to this obvious conclusion. Which implies that this was never about protecting kids in the first place. It's about controlling what people say, as always.