Well I completely agree. However, use the same logic you applied in your last comment and apply it to the second last. You'll find out that all you can apply all the arguments to the current system as well and maybe more.
Point 1 you made:
a team play all three players in one thrown game
I was trying to explain that the situation would not be worse than today where you have to train every game out of position because the same regime must be applied to all trainees. All you have said in your last comment applies equally to the current system as well. As I was trying to argue, on average teams would be a bit more competitve in the new system than they are today.
I would expect that at the middle to higher levels, there'd be even more incidence of teams completely throwing a game per week - which is common enough as it is in the middle levels for teams contemplating Cup runs. If throwing a single game would also allow you to train three players a full 48 minutes as well, it would simply add additional incentive for that. But of course, that's just as much speculation as the thought that it would improve competitiveness so we can just leave it as a difference of opinion.