Uniquely skilled is probably a better word to use. H1-Bs are meant to be used when American worker's can't be found to fill a role. I think there are more people qualified to be a mid level software engineer (even at the FAANG level) than principal mechanical engineers at Boeing.

I doubt that many mechanical engineers can become a principal level engineer at a Fortune 500 company in 3-5 years, but I know plenty of software engineers who've gotten to L4 at FAANG companies in that timeframe.

I don't think that's what they were implying, but with the way google has been going this past decade, I don't think anyone is still under the impression that google employees are highly skilled. They're the butt of tech jokes for a reason.

Leetcode mediums do not count as skill in this context.