The kernel works and so far no-one has been motivated enough to update it. The Rocknix projects offers an up-to-date kernel for a whole bunch devices including the 30 USD R36S which offers amazing value for the money (but does require an USB WiFi adapter for networking).
AFAIK that's the case with pretty much every ARM SBC, Raspberry Pi being the exception. They still support the original model from 2012 with their latest OS and it's a huge part of their success IMO.
The CPU is pretty close to rpi2 and zero W2, which can run latest vanilla Debian. Not sure why the official OS is stuck on such an old kernel.