Because fans overvalue their prospects.
You have to subsidize your roster. You can't just draft and develop and target spend and win in this league. Plus, there's just no real way of saying this as a fact. You're simply overvaluing prospects. Windows close rapidly for small market teams and there's no guarantee Frelick, Mitchell and Turang amount to anything. LIS, they aren't elite prospects.
Kyle Schwarber is incapable of single handedly lifting a team? Didn't he basically keep the NL Champion Phillies afloat this season when they were sputtering as a team? Jorge Soler is incapable of riding a heater? I mean, the man won World Series MVP for a reason (but you don't count that for convenience). Soler had a 132 wRC+ for the Braves and hit 14 HR in 55 games. You're right, he wouldn't have made any difference for us. My bad. Only would have cost us money to acquire but we couldn't take that gamble because of JBJ.