In short: you can write latest JS and have it work on old browsers because Babel will take the input and fill in with functions defined for your target version.

Recently, they complained about their funding situation https://babeljs.io/blog/2021/05/10/funding-update

OP seems to indicate that one of these paid devs isn't contributing. I didn't check GitHub myself but if you check this blog post and the tweet, you can figure out who it is.