In the US yes, but the US companies would be at a disadvantage to their foreign conglomerate counterparts in foreign markets.

Dems/libs are fools when it comes to this. They never have the backbone to take on foreign Govts. I'm totally against this because we are in a globalized world and these companies need to be large and strong to out-compete with others across the world.

Saying "we are in a globalized world" makes it seem like that is just the nature of things and not the outcome of specific policies taken by primarily the US in the post-WW2 era. Corporate concentration is against capitalism, and dealing with global competitors can be dealt with with the tools we already have, like the current administration is with trade policy.

It is not as simple as it looks. Some degree of globalization already existed for tens of thousands of years, whether through colonialism, Asia-MiddleEast-Europe trade and many more. Even though there are ups and downs in the cycle of regional/global trade, it has continued to move towards more integration, especially due to technological innovations seen in the past 500 years.

Nations that decide to close down in certain areas, may find themselves in a competitive disadvantage to peers making use of data, economies of scale, technology, labour, etc. This is something we have seen happen in history.