The title of this subject thread strikes me as odd. It would be like asking on a watch forum if all Swiss watches are junk. The firm answer is no, they are not! I have the perspective of being a builder/painter that started in the mid 70's. Before powder coating, I would get in a lot of frames for a respray (and possible adding and/or removing of braze-ons). I would always check to see how aligned they were on my cast iron alignment table. The British and French frames were most often out (although some were not). Later Italian frames would be pretty accurate after companies started using Marchetti or Bike Machinery frame building equipment. Almost every Japanese frame was aligned correctly. I very seldom had to do any correction.
Contributing to the quality of Japanese frames were companies like Nikko that made bulge formed lugs and BB shells. Trek used these lugs in the 1st frames they made in the 70's. This was a superior method (in my opinion) than European made lugs that were made by welding a seam to make the socket (that later had to be filed smooth). Top end frames later used investment cast lugs.
I was talking to one of my Japanese friends yesterday that grew up in the Midwest. Years ago he would get unwanted attitude about Japanese made products that resulted as an aftereffect from WWII when manufacturing had to start over again. He often heard that the Japanese were copiers and their stuff was poor quality. Eventually Japanese products were known for their quality. But the attitudes remained long after the quality had greatly improved.