Baseball teams try to win games.* To win games, you need good players. And since there is a roster size limit, you can’t just stuff your team full of an infinite amount of great players—even the Dodgers must abide by the 26-man active roster rule. Therefore, you would think that baseball teams break Spring Training with the best and highest quality roster available to them.
*Unless your team is owned by John Fisher, in which case, well, I hope you like gambling, scorpions, and sadness, in that order.
But pretty much none of the 30 MLB teams do that.