No code or event handlers could run while importSync is resolving. I think including it would have been a mistake. The only other thing that's remotely similar are alert() and inputBox().

IMO it would be a pandora's box of unending problems. A function doing a synchronous dynamic import creates a bad user experience. It's also a pretty rare circumstance in my experience. Dynamic imports are relatively uncommon to begin with. Having one that must be inside a non-async function is unheard of for me.

If you had your way, I think the net result would have been worse.