In an ideal world, we could have actual rotations and different lineups, but in reality, that just doesn't work. The online community being what it is makes those things basically impossible to pull off. Whether it's stacking a lineup full of lefties and backing out when you actually have to face a LHP or manipulating your rotation so that one or two pitchers pitch at all times makes those things impossible.
For every one person that would play things out as they go, there are 20 that would do anything they could to manipulate things to their advantage. That's why we're in this position to begin with: because the community forced their (the developers) hands.