It's not silly. What is more the case is that Welbeck has reached a point that he needs more games week in and week to improve.
Macheda on the other hand maybe needs that but, also could be that not impressing as much on tour could do more time with our system. Not to mention that he perhaps due to ego issues, it might be better he is at this club under the watch of the boss. Don't forget there will always be stuff said about him heading back to Italy if he is getting games etc. So his situation may have to be handled a bit differently.
Macheda also had far more time off from injury last season that whatever progress he was making could have taken a setback.
Welbeck with us has also not had a chance to play a striker role in the first team. If he continues to stay here, because he can play wide unlike Macheda, that may be the only way he gets pitch time, to be used out wide. At another club he might get a chance to play a central striker more and thus developing that part of his game.