Some years ago its been already tested, that armbian work fine with the beaglebone black: Armbian support for BeagleBone Black - Board Bring Up - Armbian Community Forums
The armbian developers are open to contribution from people who would like to add support for the board.
Is there a special reason why there is still no armbian support for the beaglebone boards? Armbian is a famous choice of many SBC-user and would probably bump up the sells of the board somewhat.
@RobertCNelson is currently building all the debian images by hand and pushing once a month new releases. Adding everything to the Armbian build system would also help save work.