What does this mean? I thought Meta has something like 80,000 employees. Meta had about 1,400 H-1B employee petitions last year. Even if we assume that number held for Meta's entire existence, that's less than 25,000 H-1B employees. Less than a third of Meta are presumably immigrants.

Have I got something wrong or is there this belief that Meta doesn't hire any Americans?

I don’t know why you think Meta accumulated most of its Chinese engineers through H1B. It’s top tier pay so most people move up to them from elsewhere.