So, obviously a LinkedIn search for exact title of "data engineer" isn't exhaustive. And as I understand your point, there's certainly no agreed upon group of skills/certification that qualify someone to be a data engineer (or data scientist, or software engineer, for that matter).

But the GP was particularly amusing to me because of its assertion that 'smart, quantitative people, regardless of industry, can build data infrastructures for startups.' I guess we could also say, there's little incentive to pay to train them (or for them to pay to train) to become a data engineer.