Even if those 29 million weekly downloads were all automated it would still imply 29 million users have setup automated jobs for building software with Babel.
No it doesn't. For e.g. how many stupid CI pipelines are set up to download it on every run? You could easily be 2 or 3 orders of magnitude out on actual number of direct users.
There are definitely many CI pipelines that download all packages every time they're triggered. For those pipelines you'd be looking at tens of installs per day (or more).