...well the difference only matters on Safari, and it is indeed surprising that Apple isn't able to provide a WebGL2 implementation after such a long time of having a (pretty much stalled) WebGL2 WIP version in their browsers.
IMHO it's understandable that the author assumed that WebGL2 is available everywhere.
It matters on more browsers than Safari. Firefox doesn't support WebGL2 on my system for example. I think it's because it uses an older version of Angle.
