I agree that a team with a deep bench will have a definite advantage in being able to play a higher-pressure game from start to finish. It doesn't necessarily mean that the team with more players will be able to maintain higher effective pressure, though, if the team with fewer on the bench is well-conditioned and well-disciplined. There is an element of strategy involved in matches against superior numbers. As someone who coaches a U18 classic girls team that more often than not has 11 -13 available players in any given match (and two matches per day) I have to say I actually enjoy the challenge of playing against the numbers advantage. Some of the best player AND character development I've seen has come from finding ways to win even at a disadvantage. I guess restrictions to enforce some degree of artificial equality are fine for some sports--after all, that way of thinking led NASCAR to such fan favorites as restrictor plates and the COT--but offhand I can't think of any other high-school-age-level team sport that restricts substitutions and allows no re-entry.
Sub restrictions may be ok for premier and maybe challenge teams (I still have reservations), but at the PMSL level, I say let 'em play. It should be about getting as much experience and field time for each player as possible within the bounds of effective competition. When you start talking about limiting subs, further limiting roster numbers, etc., we're also talking about limiting opportunities for young people who want to come out and enjoy playing the game.
I'm sorry if I just don't "get" it, but to me, the beauty of the game at this level isn't about uninterrupted flow and undisturbed aesthetics; it's about what the opportunity to get on the field and play does for the young people involved, so I'm not a big fan of restrictions that limit chances for participation. If another coach shows up with 18 players, I don't feel the need to force him not to let some of them play just because I only managed to bring 12. On the flip side, if I only have 12, I've made one sub, and there's an injury, I don't want to have to play short because the one player on my bench is restricted by a no re-entry rule.
And if a team with small numbers can learn to condition, pace and position itself to stand up to a high-pressure attack from a team with greater numbers and unlimited subs, or if a coach can bring a team with enough talented, well-trained players to sub continuously without creating weak spots in the field that can be exploited, then heck...I tip my hat to them too.
