Can you tell me how it's "equal footing" in terms of leaderboards when your players just play 26-27 minutes a game while your opponents play 10-15 minutes more?
Just because everyone is competing using the same rules does not mean everyone is in equal footing. These rules very obviously favours teams that have close games and penalize teams that are very much above the competition. As a team that's very much better than your opponent, you aren't allowed to compete to your fullest potential. If we abolish garbage time or make garbage time optional, everyone is playing by the same rules as well. Plus if it's optional, you get more control, which leads us to this:
On the other hand, the proposed way is that someone may end up complaining that his player was not the leader board just because the opponent played his entire career without garbage time.
Who in their right mind would complain about this when it's their own choice for choosing garbage time? If you choose to have garbage time while your opponent chooses not to have garbage time, it's nothing but your fault alone if your players don't make to the top of the leaderboards, coz you yourself chose to limit his minutes.