I'll be honest and say that's typical Wenger school of thinking, he's got people convinced their won't be harmony if there's a big pay disparity, that's his policy and a damn stupid one if you ask me (it's hindered us massively over the years), he paid the likes of Bendtner, Denilson etc much more than they were worth because of this.
Do Barca say to Messi we can't pay you more because other players will want the same, do Real say this to Ronaldo? No better players command better wages because they are more talented and more desirable ad perhaps more important to the team, that's always been the case and I don't believe for one minute is causes issues (except for players who think they are better than they are in which case get rid).
Some of these ideas Wenger has literally pulled out of the sky seem to have become ingrained in the clubs thinking now, this is what I mean when I say Wenger will leave this club not in a great state, he's changed this club in so many ways and it's deeply ingrained in it's culture now and changing it will be very hard, any new manager will find it much harder than normal because of all this, which is why he'll need to be given plenty of time.