[xyzzyz]

This is a reason, but there are other reasons too. For example, developing nations are often full of corrupt practices. This typically is not a huge problem for investors, you just pay a few bribes, it’s a cost of doing business. What is a problem, though, is laws like Foreign Corrupt Practices Act, which makes it a crime for US investors to pay bribes in foreign countries. I’m quite sure that it feels very moral to ban that, and it totally had no protectionist intent whatsoever when it was passed, but the practical outcome is that if doing business in a country is impossible without paying a few bribes here and there (and it is in most poor countries, low trust in institutions is one of the reasons they are poorer than us in the first place), they will not get any foreign investment, which will keep them poor.