Like I said it's a matter of accuracy.
I remember the old days and I would agree with you on cheap platforms, 2.5 bbs would equal 1 bullet. It's a bit more fair of a comparison, since at 3000 BBs everyone might as well just have one box mag instead of 42 lowcaps lol
So each mag, 70 rounds, regular old AEG, no problem.
However, if you look at how well I, for example, play with a PTW versus my old M4 AEG, you would then see it's very obvious that I do significantly better right off the bat.
So now, to maintain the same performance I need to limit myself to say 1.5 BBs per bullet.
The same could be said for me using my old VSR-10, wherein better fairness would be achieved with 8-15 round mags instead of 30.
Now we get into personal skill;
Whereas I know from past precedence that with my bolt action rifle I can shoot someone's boot cap sticking past a door frame from 80 feet and through a raised mesh catwalk. Whereas most people aren't that good of a shot.
But chew on this bone; Does having more ammo really make you any better of a shot?
Having an amazing rifle, and practicing with less ammo, will force you to learn the platform faster than knowing you have near limitless ammo remaining.
The same could be said for the platform; wherein an amazing rifle with ammo restriction will force you to up your game faster than a rifle with poor accuracy and near limitless ammo.
It's been my experience that if the rifle is inaccurate, people won't TRY to aim. And if your rifle is accurate, but you have lots of ammo, you won't TRY to conserve it. Doesn't necessarily make you a worse shot, but it doesn't make you any strategically better.
So all that being said, I'll underline my original point;
The users of BETTER guns, polarstars, PTW's, realswords, etc, would do well from having self-imposed ammo restrictions
And the users of inexpensive guns, would likely feel the playing field was more level.
Because even a veteran airsofter with a polarstar or AEG with $600 of upgrades and 3000 rounds on him, can sometimes act like a noob spraying their new AEG. And why shouldn't they, if it's perfectly acceptable within the rules?
I've seen it happen to many veterans. They get a wicked gun, carry as much ammo as they can and just go trigger happy. What holds the rest of us veterans back, I think, is that we need to feel challenged, we need the game to be more difficult.
Not that I'm trying to get anyone to impose special ammo limits, I just think it's very interesting psychology, and a very interesting problem that plagued every sport. People who spend more money, have better gear, just have an unfair advantage compared to those that just can't afford the good stuff.