Two high end sleeping bag companies sew bags in the USA- Feathered Friends in Seattle and Western Mountaineering in Marin County Ca.

There are cheap "knock off" versions of proprietary materials. Not every factory in China or Vietnam, or wherever, produces the same quality. The baffle systems you cite are NOT equal in warmth. The down itself can vary in quality.

Another advantage of the two high end companies I cited above is that they really stand behind their products. I have owned bags made from each for decades.

It all depends on your needs and budget. If you backpack a few times a year and in relatively mild climates, then a cheaper bag may be just what you need. On the other hand, if you are out 50-100 days a year and backpack in more extreme conditions, then a more expensive bag may be justified. I doubt many if any PCT or CDT thru-hikers use off-brand bags. Definitely, if you are looking for maximum warmth for minimum weight than you are going to pay a lot. Each of us had to decide how much that extra cost for an ounce saved is worth.

I am not saying there are not some pretty good cheaper bags out there. As for the expensive bags, you have to separate the sales pitch from the actual quality. High dollar is not a guarantee of the best bag; but the best bags are more expensive.