If you think fiberglass stocks are perfectly stable, you must not be familiar with the problems fiberglass stocks had on match grade M14's and how they bent from sunlight on one side. Zero's also changed from hot to cold ambient temperatures. They were no different that synthetic ones. Their fore ends bent enough to change the pressure on the barrel at its band the stock ferrule pressed against. But the wood stocked ones had no problem.
Both non-wood stock material types change dimensionally and structurally with temperature.
All stock fore end's bend from external pressure some amount relative to the axis of a receiver solidly fixed to them. It's the most at the fore end's tip and much less close to the receiver and it depends on the size and material, too. The axis and amount of that pressure depends on how the stock's held and steadied by the shooter. If you measure how much they do bend, you may well be surprised. There's no way any pressure point from the fore end to the barrel will remain constant in amount and axis across all shooting positions. In some postions, it varies more than others. And that variable gets transferred to the barrel so it's not going to behave the same across all positions.
So do you think a 30 caliber, 26" thick, heavy target weight 4.4 pound barrel's stiffer than a 30 caliber, 22" thin, featherweight 2.1 pound sporter barrel and the feather weight one should have a pressure pad on it from the fore end?