part of the problem is that you really can’t make a 9′ 7 wt. that is actually fun to fish with bamboo unless it is hollow built. Hollow building doesn’t come cheap. Another problem is QC. I’ve seen several of these old rods and own a few where they even messed up as much as glueing up some of the strips with the enamel side in (hex rods are 6 strips with enamel side out/pith in…some of these actually flipped them any which way). Some of their bevellers were not very good. Lots of different things. Some of those companies put out some really great rods though (Granger, South Bend, Heddon). But those same companies put some stinky ones too.
Read those books I told you about. Too much info to put on here, it’s all in there. Black’s book tells you the history of all these companies, some will surprise you. Geirach will tell you which rods are great.