Ridiculous example that almost never happens? Do you only watch Purdue games? Over the years, I have officiated 100's of CBB games, and have the exact play happen hundreds of times.
Watch a game that doesn't involve a team you care for....Watch how many times the secondary defender is 10 feet off his guy, or so---and simply takes a step or two, into the lane, and a tkaes a charge. OR, how many times a guy is camped in the lane, "playing" an area, not a player, and again just simply takes a step or two, and draws a charge after the offensive player has beaten his guy.
Just take the time, and watch a game----and watch it off the ball. You'll be back here telling me---"Yeah, maybe we do need the rule".
Thing is, there a few people who rarely watch the game, watching any of the action off the ball. I do it a ton. Probably b/c I am used to doing so. But give it a shot.