The distinction isn't “can possibly learn” but “can clearly and immediately understand while doing the real work”. It's one thing to sit down and play around with alternate styles, code golfing, etc. but for production work it's usually best to pick the most understandable way to reduce the cognitive overhead so when someone is making a change, debugging, profiling, etc. they're not instead spending time decoding the clever trick their predecessor (possibly them six months ago) used.

This is particularly true with religiously following functional style in languages which weren't designed from the ground up to work that way. The results usually take more time to understand and are often slower because the runtime is not as optimized for uncommon styles.