The real blame ultimately is with the RV maker.
If a RV maker specs the right frame with some headroom for vibration, full load, and day to day real weather conditions, there would be fewer problems. Lippert specs exactly what the RV makers tell them to spec, no more, no less, and that is invariably a far scrawniner frame than what should be used.
Nobody is forcing a RV maker to use any frames that get shipped. It is an integral part of the RV maker's job to inspect an incoming frame, and if it is full of booger welds or not up to par, it needs to head back to Lippert as a defective product. Inspecting a frame isn't rocket science -- any welder can look at it and know if it is suitable for use or if it goes into the reject bin. Since RV makers are welding anyway, they should be able to add reinforcements if needed if a frame is marginal.
If Lippert is so bad, RV makers should be beating a path to Norco BAL... but they are not. Norco BAL doesn't use welds, but uses huck bolts (And Huck Bobtails allow for relatively easy disassembly of the frame with the same tool that was used to assemble it.)
I would focus the blame where it belongs, the RV maker. Not that I consider Lippert above reproach, but they just make what their customers (which isn't us) tell them to.
