up to 12% of internet users still use IE11, and even more if you count lower versions. It will take them about a decade to upgrade to a "modern browser". There are still large companies who want browser compatibility down to IE 8.
That's not a matter of "browser compatibility" which is what GP complained about. The browsers are compatible, if you decide not to use them, you can hardly fault the browsers.
In fact, aside from Edge which lags a bit behind (and FF 52 ESR) all of them seem to have full ES2017 support already in their latest stable.