Absolutely.
I think not making subs can be a part of it perhaps, but on it's own obviously not sufficient. But can perhaps be a part in helping the players really understand that they can't just look to Ange, the subs or a captain to help them out. They all have to look to themselves and each other.
I think having a more experienced "standard bearer" can help. Imo Hojbjerg provided some of that. As did Kane. As have others. That on it's own isn't enough either as we've seen repeatedly.
We've had players like Modric and Bale who for themselves had great mentality imo, but were still part of a non elite mentality as a group here. Go to Real Madrid and fit right in to a group with great mentality. That has to be built, developed, that takes time. It's not fixed by any one thing. We can point at managers, captains, leaders whatever and that is important. But for a truly great mentality to set in it has to be the squad as a whole.
For me (speculatively for sure) Ange's non substitution symbolises something important. The players have to learn, if not they will sink, somewhere, somehow. As they did in a limited way against Brighton. With that Ange too will sink of course. But that is the reality. There's only so much he can do if they don't learn/develop on this. A solid part of that responsibility has to be on them. Ange, imo, has to be willing to fail on this. He has to be "stubborn". Because if he is desperately trying to paper over the cracks and get "false results" he's trying to take the part of the responsibility that has to be on the players for them to develop on this.
I don't know if Ange is or can be a great manager in a big league. But to me, looking from the outside, he seems to be trying to instill what great managers are able to instill and what imo has been really important for their success.
I quite like also with this what was brought up on the pod. The initial meeting post game is for the players, not Ange and the coaches. They can't just look to him for solutions, they have to find solutions.