> Constant pressure to hit quarterly performance targets meant that machine quality often suffered. In some cases, machines would be shipped out the door unfinished so the delivery could be booked, and assembly would be completed by service technicians at the customer’s location. In his history of the American machine tool industry, Albert Albrecht states that “the actions of these larger corporations and conglomerates, under the leadership of financial MBA’s, perhaps more than any other factor, contributed to the restructuring and decline of the US machine tool industry at the end of the 20th century.”

In short, the MBAs happened. Clueless management was brought in who then decimated anything they did not understand. I.e. everything. Aided by Reagan policy to aggressively outsource manufacturing from the nineteen eighties US manufacturing just imploded.

Just speculating here, but by the time the Japanese and the Germans caught up and got really good at machine tools, the metric system would have become an obstacle as well. Because the US insisting to do everything in inches, foot pounds, and what not doesn't translate very well internationally when you start outsourcing all your manufacturing. Outsourcing meant manufacturing standardized on the metric system using equipment and parts not made in the US.

Just speculating here, but I imagine that all that combined lead to a natural preference for non US based manufacturing companies that took over from US companies to not use any US made equipment or parts. So, manufacturing became predominantly metric based and that would have affected standard components, screws, bolts, parts, etc. All made by non US companies standardizing on all of that.