This is in fact the real reason that we still have the airplane mode restriction. A phone at cruising altitude can see and try to connect to a huge number of c

This is in fact the real reason that we still have the airplane mode restriction. A phone at cruising altitude can see and try to connect to a huge number of cell towers at once. Like, orders of magnitude more towers than it would be able to see even from the top of a mountain. Plus, you're constantly disconnecting from some towers and connecting to new ones. This puts a strain on the cell network systems. One person won't have a negative impact but then you multiply the problem by the number of people who fly daily.