I feel like there's a bit of an overreaction going on here. Samper is clearly better than Gumbau and Camara. No matter what you think of Lucho, you can't think he's stupid enough to think otherwise. Injury wise our entire midfield + backups are all completely healthy, so any players called up won't get a sniff of any minutes anyways. Whenever Samper has been called up, with only one exception, Lucho has subbed him onto the game. With this in mind it's pretty easy to see what's happening here. Samper is obviously our best midfielder with the B team but moving him along too quickly or calling him up for a game he won't get minutes in will hurt his development. We don't want another Bojan/Munir/Deulofeu/Adama situation, now do we?
Plenty of our players have come to the first team after playing in the third division and they are doing just fine. Building on the skills they'll need for when they get promoted is more important than challenging them while they play. The real challenge can come from playing in the top flight, with teammates that aren't largely incompetent. If Samper works on his defensive game and just keeps on improving his distribution Barca B could lose every single game 10-0 and he'll improve, or they could win every game 10-0 and he'll improve. He's not a forward who has to contend with defenders who are better at tackling or a CB who has to content with pacier wingers.
Samper will be fine.