I think both are equally bad for two different reasons. Someone who shoves every hand they play just destroys all value because they are going to get called by a hand that is beating them, so they lose value on good hands and get knocked out on hands they are beat (if they don't suck out. People who limp every hand are bad for the fact that they do not isolate to play against a few players. Isolation is key to being able to manipulate and range properly. The best poker players use every tool, limping, shoving, small raises, small bets, big bets, etc. to their advantage. They know what the best play for a situation is, so using the same tool for every situation would be like trying to send out a team full of punters to win a football game. They'd dominate when they have to punt, but would suck every other time.