That's a really good point. I was about to disagree with you but then I created a thought experiment.
Thought Experiment:
I wonder what the JS landscape would look like if ES6 Modules were introduced as part of ES5 about 8 years ago? I could definitely see how that would make classes fare less appealing if we already had a great module system (sure CJS existed but browser didn't support it).
Looking at the timeline of when these features were implemented in all major browsers:
* ES6 Class[0]: implemented 2.5 years ago * ES6 Modules[1]: implemented 1 month ago
[0]: https://caniuse.com/#feat=es6-class [1]: https://caniuse.com/#feat=es6-module