Nobody believes all our prospects are no-miss players, that's a strawman argument you keep having with yourself.
You also never seem to consider that maybe, just maybe, the Twins are currently rostering several players who have a demonstrated lack of success at the MLB level. You seem to think it's better to rely on players who have played at MLB before, even if they were awful, than give a young guy a chance because all prospects don't work out. This sounds like Derek Falvey thinking! Worked out great for him.
I would think by now this current Twins "core" has demonstrated to fans that they just aren't good enough, and they need better players. The roster needs to get significantly better. ESPN just did a list of the top 50 players in baseball, the Twins had 0. They aren't good enough. Continuing to hold back promising prospects in order to play older, worse AAAA players is a really poor strategy for a middle revenue team like the Twins.
There are 3 ways to get better talent: trading assets, spending $$ in free agency, and developing your own talent. The Twins don't spend on high end free agents, so we are down to trades or development. I'll let you determine how well trading has worked for this club - similar to prospects, some work out, some don't. Teams like the Twins absolutely cannot be successful without developing and playing their own talent. Ask the Brewers or Rays.
Enjoy the battle for 77 wins though.