There seem to be some interesting misconceptions in this thread.
From my reading of fin studies and from my personal experience, full foot fins are superior to open heel fins with respect to transfer of power from foot to blade. With an open heel fin, the foot is moving around in the foot pocket (and inside the boot) much more than in a full foot fin foot pocket, and all that moving around in the pocket and boot is a significant loss of power transfer.
Most scuba fins are available in either full foot or open heel. Other than the foot pocket, the dive fins are the same blade attached to a different foot pocket so I can not see how a diver could say these full foot scuba fins are primarily made for snorkeling.
There is a difference between what some call stiff and others call flexible; my Gara2000 freedive fins are so "stiff" the tip of the blade can easily make the person behind me bleed if they get too close, but they are also so "flexible" that when standing in waist-ish deep water a medium strength surge often causes the tip of the blade to touch my shin. Very few scuba fins are stiff enough to draw blood and very few are flexible enough to touch your shin due to medium surge.
Hot sand is the only sand issue that ever makes me wear booties for beach diving. I used to try to re-educate every diver and snorkeler I ever saw backwards shuffling into the water from the beach with their fins on. Now I find this Sea Hunt-ism to be quite entertaining and only re-educate fin donning if they are paying me or if I am flirting
Modern full foot fins have very comfortable foot pockets; most divers will not need protection from blisters in properly fitting full foot fins. Those with very tender feet could use neoprene socks, but might need to fit the fin with the socks as a too tight foot pocket situation is not optimal either.
I use my bootie fins when I have to walk/climb over sharp volcanic rock to start/end the dive. If I can gently enter the water with bare feet deep enough to float, I will seriously consider taking my full foot fins.