'BobbyJo didn't say "no margins", they said "margins would tend toward zero". Believe it or not, that is, and always has been, the entire point of competition in a free market system. Competitive pressure pushes margins towards zero, which makes prices approach the actual costs of manufacturing/delivery, which is the main social benefit of the entire idea in the first place.

High margins are transient aberrations, indicative of a market that's either rapidly evolving, or having some external factors preventing competition. Persisting external barriers to competition tend to be eventually regulated away.

The point of competition is efficiency, of which, margin is only a component. Most successful businesses have relatively high margins (which is why we call them successful) because they achieve efficiency in other ways.

I wouldn't call high margins transient aberrations. There are tons of businesses that have been around for decades with high margins.