I don't think it's a big deal. I mean yeah it would be nice to just completely decimate hoards of fallen or hive that are level one or two, but it really balances the game in my opinion. The guns aren't supposed to get better as you level up, your abilities do though, that's the balance. Plus it would get super boring very quickly lol

If I go and shoot a level 2 mob with my level 21 (not exactly 20 level difference but still the point is valid) Warlock and use a Scout Rifle I still kill them in 1 hit to the face. Who cares if it is 375 damage or 375,000? A head shot is a guaranteed one shot kill either way. I can see them putting a damage cap due to the whole "no cave shooting" mentality that Bungie has adopted recently. If you kill anything with stray bullets to anywhere on the body, people would do NOTHING other than camp spawn points and keep holding their trigger until they get a Legendary Engram. No strikes would be done, the Raids wouldn't get enough interest, and not to mention that lower levels trying to get their bounties in certain areas wouldn't be able to because high levels would be "stealing" them all for themselves. It's all about balance

That's exactly what happens. Likely to stop high level people one shotting everything throughout the whole story to carry friends through. Also a level 2 dreg gives the exact same experience as a lentil 28 dreg.