············What incentive would a team like Manchester United have for supporting any change in the status quo?··········

I see no virtue or point in this argument. If the change were voted thru by the competent authority, then Man U would have the same option as any other team: to accept it & abide by it; or to bugger off and ~ ah ~ play with themselves.

There was, remember, considerable opposition, on much same sort of grounds as those above to this change I propose, from various entrenched interests, to the changes in the back-pass to goalkeepers rules not that many years ago: it was a fundamental alteration to what had gone on as long as the rules had been formulated. But it has indubitably improved the game and I don't think anyone regrets it now.