It's not the edge bevel that determines or limits the angle of board tilt, it's the rider's use of angulation in the case of dynamic carving and inclination in the case of basic carving. A degree or two of bevel on 5MM wide metal strip on the edge of the board has absolutely no power to "lift the base off the snow" or prevent the rider from tilting the board.
If you have a 0 degree base bevel, an edge angulation of 1 degree is achieved by a 1 degree tilt.
If you have a 1 degree base bevel, an edge angulation of 1 degree is achieved by a 2 degree tilt.
If you have a 2 degree base bevel, an edge angulation of 1 degree is achieved by a 3 degree tilt.
Last time I checked, snow isn't a granite surface where I ride so the track made by a 3 degree tilt is thinner than a 2 degree tilt is thinner than a 1 degree tilt. Therfore...base beveling LIFTS more board off the snow! THUS, as you have observed yourself that being "slightly on edge" is faster than "flat basing", the more base you have touching the snow, the more suction, friction, whatever....slowing you down ever so slightly! Is that really that hard to understand?
You can say whatever you want about edge beveling, but the recomendations are for a reason. And is not "just for beginners". I was an expert rider when I started beveling and I put a 3/3 bevel on my Lib Tech Dark Series ADVANCED RIDING board. And it helped me "flat-base", spin easier, land without catching, etc. And I had FUN with it without worrying about catching an edge as much. Now did it reduce performance when carving down double black ice trails? Maybe...but I moved past that and focused on fooling arround on easier trails instead! I mean, I thought we were talking about teaching BEGINNERS anyways, so why you just want to argue by bringing up advance free-riding topics?