I am fairly sure I recall reading somewhere that because the engines on the Max are mounted farther forward than previously, there is a region of high AoA and high thrust where the pitch-up force increases with AoA.

I can't vouch for this. It's possible I misunderstood it; it's possible the source was misinformed, though I seem to recall it was written by a pilot. But I have trouble imagining what lesser problem would have required such a heavy hand as MCAS to fix. If it were really just a matter of the controls going light, surely that could have been cured with motors that were not so powerful as to be almost impossible to overcome.