They haven't even finished moving to OOUI. Actually, if they'd just bothered to document OOUI properly in the first place, would they need to move? As it is,

They haven't even finished moving to OOUI. Actually, if they'd just bothered to document OOUI properly in the first place, would they need to move? As it is, they'll now have three concurrent systems (jQuery, OOUI and Vue). It's like GTK 2,3,4 all over again.