This means "chinese" mini mills^1 which require a lot of manual labor to collect the steel. This is not a technology problem, but a manpower/safety race to the bottom, that the US couldn't effectively participate in. Unions may have prevented useful compromises, granted.
New technology was not a priority, because it wouldn't help the situation. It's not like steel makers stopped doing cost/benefit analyses for decades.
A Japanese owner looks like a strategic political move, given Japan's place in the world theater. The tariffs against steel were removed for the US and Japan at the same time circa 2022. Coincidence?
^1 https://www.reuters.com/article/us-china-steel-overcapacity-...