Do I Need Pillars in my Stock?

Pillars are not really needed in any fiberglass stock. Pillars were invented for wood stocks because the wood will crush between the guard and the action.

The reason we have pillars with the M5 is to set the exact location of the guard so it feeds correctly. 

On an M4 or Obendorf style guard (that’s what a swing down floorplate guard is called) the guard is usually made flush with the bottom of the stock and the feed lips in the action do all the rest, 

there is a lot more flexibility in the system because the feed lips are in the exact right spot in the action, the guard just holds the follower assembly and the bullets.