First of all, SUROS is still boss, and ARs are still very good (hell I still use high ROF ARs and do very well with them). They only difference is that pulse rifles are usable. The nerf was 2.7 damage OVER TIME. Seeming how auto rifles fire very fast, they every round do quite a bit less damage to meet that quota. Therefore, it only really takes you an extra round to kill someone (maybe two, if they stack armor and you only land body shots) which is extremely easy given how fast it fires and controllable the recoil is. It still does 31 per headshot (more than most pulse rifles), and 25 per body shot (far more than most pulse rifles, only beaten by Evergreen 1.1, Red Death, and Three Little Words). SUROS is still a boss gun. It just has more competition now with Red Death and Bad Juju actually being viable. Truth be told, of all the exotic primaries in SUROS's tier, three of them are hand cannons, which would have been in SUROS's tier prior to the nerf. Finally, your real world analogy is rough at best. Apart from the fact that it would make the game extremely unfun to play (keep in mind that at launch they were much closer, Bungie had to nerf ARs like crazy and buff PRs and SRs to make them more balanced), real world guns don't all "do the same damage." Auto Rifles would likely be comparable to submachine guns. Submachine guns in techincal description are automatic rifles: they are recoil operated long-guns with rifled barrels. The name "submachine gun" was made to distinguish the kind of round they operate with (rounds originally chambered for pistols). The low-velocity, smaller caliber round makes the recoil much easier to fire at fully automatic; however, would make it much more difficult to penetrate barriers compared with traditional rifle rounds or for them to keep their velocity at range. Sure, an MP5 could penetrate the kevlar weaves and ceramic plates of modern body armor, but it would take numerous rounds to do so. Now compare this with the space age materials and armors worn by Guardians and aliens... the comparison would not be to dissimilar. Now compare Pulse rifles to smaller caliber rifle rounds such as 5.56x45 or 5.45x39. Sure, they have more penetrative power and range than those pistol rounds, but with added recoil. You keep them in burst fire to help control that recoil (like an M-16 A2/A4). They also lack mass to do as much damage as a larger round, and would be more likely to fragment through barriers (much like real 5.56 rounds when they go through glass or similar materials). See how the analogy works? Now look at SRs. You could compare them to large caliber rounds like the 7.62x51 or 7.62x54. Since they have more mass and velocity, they would have more penetrative power and would remain intact through barriers. This added power comes with added recoil, meaning that you probably wouldn't want this chambered in fully automatic (which is why most professional modern day armies don't use this for their standard issue rifles.) Another great analogy. In short, Bungie doesn't keep them doing all the same damage because not only because it wouldn't be very fun, but it also wouldn't be very realistic either (besides, would we be playing a game based around shooting aliens in the face and disintegrating people with lightning- infused punches if we wanted realism?)