Is it really easier to find accurate loads for thicker barrels?

[kmon]

There is some truth to that hypothesis IMO but individual rifle barrels can always be subjects to themselves but generally speaking yes. One other thing that makes load development go easier is larger diameter barrels heat slower so more shots can be made with them than the thin barrels that heat up a lot faster. Also as barrels get longer they are less stiff no matter what the diameter is. I find short heavy barrels will at least have wider accuracy nodes than a longer barrel of the same diameter.