it would almost certainly lead to a huge spike in fatigue induces injuries when guys can't get out of innings. Stupid idea. You don't get where you want to by just forcing the square peg into the round hole, you have to recognize that the problem is NOT the pitchers - they are giving you their all, it's the GAME. Pitchers will go deeper when you change the game to reduce the stress on them, not by increasing it. Idiotic suggestion.
If you actually want to use fewer pitchers but are unwilling to fix the game, then adopt the ST rule, let a pitcher sit down after 25-30 pitches in an inning and then come back into the game next inning.