The one situation where setting the altimeter to "zero' before flight
makes sense is flying a purely aerobatic flight. You will never be
towed high enough to bust airspace rules. You must be totally focused
on how high you are above the ground and to make sure you do not bust
the 1,500 floor for aerobatic flight. With so much going on in the
cockpit, setting the altimeter to zero makes the scan of the panel
very simple.