Why aren't players allowed to reenter a game after they go out?

Answer 1

At first this question seemed silly to me, but it actually is intriguing. I suppose that the rules being the way they are may just reflect what the game's creators felt was best. The only other thing I can think of is that Baseball is a rare sport in that a player will not become winded and benefit from a rest on the bench. Therefore there is no need to remove tired players and re-insert them in the game. No strategical benefit is gained from this rest. It all has to do with the pace of the game and the availibility of frequent "down time" even if one does get slightly winded.