He quite clearly states in the article he would ‘leave out classes’ (i.e. implementation inheritance). You didn’t quote the clearest statement in the article, just preceding your excerpt!?

Again on interfaces, sometimes less is more. Many people prefer the inverted interfaces of go, declared at point of use. It’s fine to prefer the opposite, but these are deliberate choices, not mistakes or failures.

Re inheritance simplifying a design, it does the opposite in my experience, unless by simplify you mean hide program flow and state.