Why is it only possible to type with index fingers on the virtual keyboard?

I was very surprised to discover that hand typing (direct interaction) on the virtual keyboard (OVRVirtualKeyboard) was only possible with index fingers, i.e. other fingers don't register any contact with the keyboard. Why on earth was that design choice made? If it's to mimic other input methods which use single contact points for each hand (controller, ray) or to minimise false positive touches with the other fingers because hand tracking isn't sufficiently reliable, why not at least include configuration options in the OVRVirtualKeyboard script to toggle direct interaction support for each individual finger for when tracking becomes more robust or simply if users want to use multiple fingers to type?

But maybe devs at Meta code with their index fingers only. That would explain a lot about how the development experience for the Quest was designed.