When you don’t use transpilers, you have to write ES5 code. No-one wants that.
Even in 2020? Isn't ES6 standard now across all supported browsers?
that might well be, but just recently i got a crash report and it turned out the user had some "unsupported" version of Safari... and i'd rather transpile/polyfill than be that site that asks you to upgrade your browser to use it
(funnily enough, it actually parsed ES6 stuff fine, but was missing the `Object.fromEntries` method)
No. And "ES6" is itself a vague term. Browser support for features and syntax varies considerably and changes constantly.