In general, most iOS devices are forced to use/link their proprietary JS vm API implementation. While Babylon makes it easier, it often had features NERF'd by both Apple iOS, and Alphabet Android. In the former case it is driven by a business App walled garden, and in the latter it is device design fragmentation.
I like Babylon in many ways too, but we have to acknowledge the limitations in deployment impacting end users. People often end up patching every update Mozilla/Apple/Microsoft pushes.
Thus, difficult to deploy something unaffected by platform specific codecs, media syncing, and interface hook shenanigans.
This coverage issue is trivial to handle in Unity, GoDot, and Unreal.
The App store people always want their cut, and will find convenient excuses to nudge that policy. It is the price of admission on mobile... YMMV =3