People who start out with linux should use that. Most companies, particularly HNey startups, should use that and nothing bad will happen.
Most people don't have to care about portability, shouldn't use /bin/sh, and shouldn't learn about Almquist. Your advice does not favors to the bulk of people who just need to get shit done.
If they do wind up working in an environment where it is important, they can teach themselves the differences at that point, or else ask someone like us to review their code (and there's an automated linter out there).
You aren't the Main Character, most people don't need to care about the same things that you do.
Almquist is in Ubuntu for two reasons: speed and standards compliance.
These may not be important to you, but they are to a great many people, and the horrible advice in this case is to disregard these factors.