Who's to decide what's best for their commute?
Does the experience of any other rider matter?

The answers are: That individual rider, and only when they discuss identical equipment or conditions.

I commute on a Kona Coiler Supreme, full suspension MTB, 2.1 tires, and I absolutely could not care less what anyone else thinks about its "efficiency". If you, the doubter, are such a p()$$y that you need to ride easy all the time, then by all means, do so. MY commute isn't just an A-to-B, it's a RIDE. EVERY ride I take has two purposes -- to go where I want or need to go, and to enjoy the journey. The Kona enables me to do that like no skinny-tired bike can.

The Japanese have said: "It is not the destination that matters, but the path to it." Time on the bike is ALWAYS quality time, to be treasured.