As mwr01 wrote, Monte Carlo styled stocks offer a slight benefit for taller shooters or shooters with slightly longer than average necks to shoot with a slightly more naturally erect head and neck posture.
The operative word here, is "slight." Most Monte Carlo stocks, given a comb that is parallel with the rib, drop the heel of the stock 1/2" to 5/8" below the level of the comb. That is why the benefit to taller shooters is only slight.
Most tall shooters need a pad adjuster, which enables them to lower the recoil pad more considerably than a Monte Carlo stock can.
Two things cause differences in how high guns shoot (their POI verses their POA). One is the slope of the rib toward the muzzle, and the other is the height of the comb relative to the rib.
The style of the stock has very little bearing on how high guns shoot. Non Monte Carlo stocks can (but rarely) have parallel combs and they do not always have parallel combs. It all depends on what the stock designer hasdin mind when considering how to design the stock for a particular model gun and shooting discipline.
The stock dimensions chosen as well as the style of the stock are the stock designer's and the marketing department's estimate of what will be most likely to appeal to prospective buyers. Sometimes they're right (Remington 1100. 870, 1187, Model 12) and sometimes they're not. (Enter stock fitters, stage right.)