A private equity firm bought cone mills in 2016. They simply made an economic calculation that the floor space taken up by the white oak selvage looms was not profitable, so they closed them down and sold them off. Levis although one of their main buyers of white oak, was also in the process of going public. As LVC only makes up a fraction of their lines and profit, they chose not to buy the white oak looms. They had also been planning for this contingency for many years, developing alternative fabrics in Japanese mills.
There is a ton of info on this over in the LVC thread all by members who are more knowledgeable than me on the matter.