He literally said it's the MMT. Lmgtfy: https://www.investopedia.com/modern-monetary-theory-mmt-4588060 and it doesn't even say that companies can't get loans.

It just makes it harder to take on debt if you don't control your own currency as a sovereign state. EU countries are a political union but not a clear fiscal union, with their own treasuries but also the ECB calling the shots and it means that member states can have sanctions imposed on them, like Greece for example.