MTMilitiaman, yes, differences can just be differences, but in many cases differences can also make one thing better than another. If differences never made any difference, we would not make any progress. Flintlocks are different than current rifles, but by no means are they on equal ground.
The force that acts on the case in roller-delayed blowback occurs in the chamber, and on the case itself, not in the rifle action. It also only occurs after pressure has dropped to a safe level and the bullet has already fired from the barrel.
GSUeagle1089, the roller delayed blowback design has less moving parts than the M-16. You've got that backwards. The blowback design is also more accurate because the action is more direct and consistent, so you've got that backwards too.
Lastly, how often do individuals clear houses? That's the job of armies and police forces, not the individual rifleman. As an individual, it's much more beneficial to own a .308 rifle that is effective at greater ranges, and for hunting, rather than a short range combat assault weapon.