The Remington 700 series of rifles dating back to 1946 were the 1st budget rifles. They were harshly criticized at the time for using a steel tube for an action instead of a machined block of steel. The recoil lug is a washer over the barrel, the bolt handles were brazed on, they used cheaper plunger ejectors, stamped sheet metal extractors and cheap stamped checkering on the wood. All of these design features were considered manufacturing shortcuts and a cheap rifle. Savage took the concept several steps farther with their floating bolt head.
Yet today most consider the 700 and Savage 10/110 rifles to be top tier rifles and the others are now budget rifles. In my experience some of the steps on the original 700 series have proven to not only make a less expensive rifle, but a more accurate one as well. Same with the floating bolt head on Savage. It was intended as a cost savings measure, but has proven to be more accurate. Todays budget rifles are no different. Some of the cost savings are proving to make for very good accuracy. In my experience most all of the budget guns shoot as well as the top tier rifles.
The disadvantage is long term durability and long term value. Even the 700 series of guns won't hold up to harsh, long term use as well as older traditional designs. By the time you get to todays budget guns most of them cost more to repair than the gun is worth if anything breaks. While they are accurate,reliable and durable enough for most casual shooters I'd not want any of them in my hands on an expensive hunt or if my life depended on it working.