The "wildly popular" part came when people realized BRCM was dumping these boards cheaper than any existing Linux SBC at the time. The educational angle is long gone.
I would agree that most of the Pis sold are not used for education, but that doesn't diminish their importance in that area.
https://forum.armbian.com/topic/12656-csc-armbian-for-rk322x...
People immediately MitM'd these devices to get unlimited free bonus stuff, and the forum was copyright struck to hell.
These devices are programmed so badly that once you give any user any modicum of control over them, you can bypass almost every restriction your TV provider can think of. Modify one or two files and you've got an excellent piracy box.
Personally, I think this whole situation is terrible and I think that it's up to providers to fix their shitty DRM, but legally speaking these boxes don't become your property.