Closed as not planned
Description
If a feature has a known good polyfill, fallback, transpilation, then it can become safe to use / learn much more quickly.
I don't think this should be taken into account when considering if a feature should be in Baseline or not.
I do however think it is valuable to record which features have poyfills, fallbacks,...
MDN already adds links to core-js
for some features : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at#see_also

It might be interesting to do this the other way around.
That polyfills, fallbacks, transpilers advertise which features they support in a format that is compatible with feature set / baseline?