Well the Yanks can't sign everyone if there is a cap on how much they can spend - and their allowance will be on the lower end since they're among the best few teams every year.
Still - the system is a total sellout by the small market teams.
what I'm saying is, if you're a high schooler or college player, and you know you're not going in the first couple of rounds, why not just make your team preference clear? Worst case, someone else drafts you and you go to/stay in school