Out of curiosity what are we assuming to be the basic kit of tools available to the cabinetmaker? I wouldn't consider myself a highly-skilled woodworker but definitely posses more than an adequate amount of skill to efficiently produce kitchen doors. The type of available tools really dictate the production process. I would argue that having a shaper / router table and a power feeder I have available at my disposal, I could produce cabinet doors (with various sticking profiles) as quickly as your method. Stock selection becomes a touch more difficult, but by taking thirty seconds to create a plan of attack (and I'm assuming because you mention grain matching, you're not going to paint the cabinets) this could be easily accomplished.
Now, if I only had a wide belt sander at my disposal.....
I completely understand the need for quickly (and more importantly, efficiently) made cabinet doors and biscuits definitely add speed to the construction but you'll need an extra clamp (or two) for pressure to be applied across the joints. MDF is much heavier than say a piece of similarity sized plywood and will definitely make tall upper cabinet doors more hefty. MDF is also more expensive than plywood.
And, regardless of quality/price, MDF is a bear to work with in terms of dust control and its effect on tooling.
I think I'm correct in saying that most kitchens are remodeled / renovated every 20 years or so--with that in mind, biscuits should hold up over that life time. But I don't think the strength of the joint was part of your argument.
just my $0.03
cb