My first foray into reloading was with a Lee Loader, except mine had a dedicated 38 Special hand primer instead of the whack with a hammer type (it was a MRC which was a company started with the break up of Lee's original company in the late 70's), then my next was with a RCBS hand primer that was with my Rockchucker kit.
So the high primer syndrome never showed up for me until quite later with Wolf primers and new Winchester 45 Colt brass, and it was definitely high primers caused by slightly over sized Wolf primer cups in tight primer pockets.
The primer compound has to be preloaded a between the primer cup and the anvil, in other words the edge of the primer cup has to bottom out on the pocket bottom, then with slightly more pressure the anvil is pushed into the primer compound, if either doesn't happen, primer doesn't go bang.
I may get jumped for this statement, but you can feel both happen with a hand unit, you get the feel primer cup bottoming, which is pretty solid, then a secondary squishy feel, which is probably the top of the rounded edge of the cup flexing, but in doing so preloads the compound between the two metal components.
I like the Lee unit because it uses 1 digit (thumb) compared to RCBS Lyman an other that use 4 fingers.
I don't load for competition so the need for speed is not there.
Just my theory.