Yes, that can be one reason. At the lower price range, manufacturers can build bicycles using 4130, but skip out on some of the other good measures I mentioned, such as butting the tubing. They may also do other things, such as buying cheap stock of 4130 tubing despite it not being the "proper" tubing for the application.

Sometimes, on the low end 4130 is simply used as a "selling point" rather than a platform for a really great frame. Cut from the came cloth, but tailored into something different.

RE: LHT:
The LHT is built with heavier tubing than say, a racing bike, in order to retain proper strength and stiffness for loaded touring. It is also a mid-range bike, a great value and a great bike, but not quite up there with some higher end units. I believe higher end stuff is relegated to smaller scale, specialty production now. The Miyata 1000 was a nice bike.