A flash hider such as a "3 prong" achieves the same affect with no moving parts, also suppressors can pretty much eliminate all flash and offer hearing protection and additional signature reduction by reducing the db levels and changing the pitch of the noise.
Yeah for a fraction of the cost in complexity, weight and issues with consumables a suppressor does all of what they were talking about and more. The US army is in theory going to a new rifle and issuing suppressors to every (frontline) infantry unit with the NGSW contract.
(We'll see how widely the new system and everything actually gets deployed but it was an important part of the whole program at least)
Why not just build one in? I guess I'm accustomed to assault rifles having flash suppressors because the one that I've actually handled and lugged around and shot with, the Valmet RK 62, does have a suppressor built in, a distinctive feature [1].
I'm not seeing anything about a built in sound suppressor just a flash suppressor which is a fairly common feature on modern assault rifles and their civilian variants. You don't generally build in a suppressor because they're technically wear items as the hot gases will slowly erode the baffles over time. That plus their extra weight and cost meant most militaries only issued them to units that were built for stealth missions in the past.
A bit yeah though they went from 20-inch M16s at the beginning of the GWOT to 14.5 or less as the main weapon so there was space to slap a suppressor on but you'd give up the maneuverability gains of losing that length. The NGSW winner is pretty short barreled before the suppressor is added and it required particularly spicy (high pressure) ammo to still be effective at that short of a length.
