Yes, and it's especially true of the AR's! Just think of the millions of dollars and many sleepless nights the design people and Mr. Stoner must have spent trimming every single excess fraction of an ounce off the rifle, and all the "improvements" that have happened since have added weight! The civillian HBAR weighs damn near as much as an M1 Garand!
If I am going to carry a 9 pound rifle, it's going to be in a major caliber, like an FN-FAL. On the other hand, in a 6-7 pound rifle, the .223 is just right. The modern AR with all the options is just perfect for someone with delusions of adequacy who has watched too much TV. Advertising has lots of people believing they can have something for nothing, and it is no more true now than it ever was. All you have to do to sell some new accessory these days is paint it black and call it "tactical" and they will stand in line to buy them. Barnum was right, there really is one born every minute.
The stripped down old SP-1 will do everything these hot-rodded "swiss army rifles" will do, and it's about 3 pounds lighter to boot, thereby closer to the principle of a real "assault rifle".It's also about a third of the price. A 9 pound AR would be a main battle rifle in a light caliber, and that just doesn't make sense.
IMO, put the money you save by buying an older, lighter, rifle into practice ammo and you'll come out far ahead. Be smart, not sexy in your choice of rifles.
Ok, I got my Nomex on, flame away!
(BTW, it ain't black!)