They started using belts because their favoured Cam gear drive was too expensive to manufacture. And probably too heavy. But that was before you could get reliable CNC machining done almost anywhere in the world.
Perhaps a return ...

Belts are cheap, the drive gear is cheap and easy to design, you don't need as many oil seals etc and they run quieter than chains.

Cheapness is the thing - plus they need regular servicing and guess who gets the income from that servicing!!