Let's remember that the military adopted rails for mounting various types of optics, lights, lasers, etc for a large and diverse user base. It's a basic assumption the weapon is a standard 2MOA chrome barrel with service ammo, effective range is 500m or so.
That's a 10 - ten - inch group at 500. Good enough for hunting and combat. If you want a 3" group at that range, a free float will only help if the barrel, ammo, optic, and shooter can deliver it all up first.
That's the whole message left out of the marketing hype on free floats, and the myth of military spec gear. It's NOT always hyper cool accurate, in this case, it's an institutional compromise - mount a bunch of stuff on the weapon by a lot of different users.
As most of us prior service are very aware, all that rail space isn't locked up with a lot of dead weight gear that isn't mission essential. Nobody wants to carry a 12 pound combat carbine, even KAC is in print saying the average civilian shooter has no good reason to have one. Most of the real world pics of troops in the box show empty rails. Most of the ads hyping the merchandise show photogenic aryans with leading edge kit and loaded rails. Yes, I'm calling out the race card, the Army has a significant number of other ethnic groups well represented. If the pic doesn't show skinny young under 23's with an integrated team, IT'S HYPED ADVERTISING, official or not.
The weapons in that pic are then subject to enhancement for the photo shoot, not what real troops use for that situation in their daily mission. If it's a high noon photo, how many times do you see NVG's, laser's, and VFG's mounted up? Complete BS, the gear is stowed in the pack to protect it and keep it dust free.
Same people who shoot for Nike shoot for the military equipment ads. If that sounds a bit cynical, it's coming from a viewpoint not blessed with being dropped off at the Mall with Mommy's debit card. When every single piece of kit comes from a shooter's own blood, sweat, and tears, you get serious about what it really delivers.
Rails/free floats have not MOA improvement guarantee, it's significant because it's never mentioned in the ads. Just blonde haired blue eyed buffed out thirtysomething psuedo warriors posing with the tricked out goods.