Why not implementing full ICU Number Skeleton options?

[floratmin]

I see that most of the options of ICU Number Skeletons have equivalent options in Intl.NumberFormat. But I do not understand why we fall short and do not implement the full spec. There are libraries for c++ and Java which implement all options (they also generate Skeletons) and it would take out all the rough edges when this spec could also be fully implemented by Intl.NumberFormat. Maybe there could also be a switch where users could opt-in to use the full ICU standard.

[sffc]

Support for skeletons, both number and date, may come as part of Intl.MessageFormat, which is at Stage 1 (https://github.com/tc39/proposal-intl-messageformat)