You become dependent on the supplier.

The downside in general is that other countries lose production capacity in steel, heavy industry, semiconductors, machine tools etc - industries that took decades to build and can't be easily replaced.

Also they gradually lose the ability to meaningfully innovate in those sectors because there's no grounding against production reality anymore.

This has geopolitical consequences further down the line.

If you actually believe this, then what is your explanation for a manufacturer to do this?

Do you think they are just stupid?

the currency eventually collapses