Manufacturing became less relevant
Let me add marketing into the mix.
WW2 drove internationalism. It winkled people out of their little countries and showed them other worlds, other experiences, other ways of doing things. This also opened up markets for the countries and corporations who were able to capitalise on them.
The 1950s marked the beginning of the era of the international brand. Brands had existed in America since 1910, but for their domestic market. Suddenly they were everywhere.
Manufacturing was decoupled and took a back seat - it was no longer the key to success as a company. It marked the end of the power of unions to control the price of goods, the speed of manufacture and the relationship between manufacture and market.
This was massively helped by revolutions in communication. Suddenly the world moved into colour as colour printing became economic and colour TV started to gain traction - both leading to a massive explosion in marketing success.
This directly led to the Japanese and later Chinese manufacturing boom as the brand became paramount and where and by whom it was manufactured no longer mattered.
This led to a 50s boom for cheaper UK regions, then a boom for lower wage regions of Europe and eventually, as transport improved, the growth moved away to lower cost regions of the world. End of boom.