I missed this initially, so a bit late with my reply, but its Ubuntu-Mate 16.04. Never was an issue until the Specter/Meltdown stuff hit. Now it seems every other update installation pops up "reboot required". I've been keeping my wife's computer up to date as she is not a very sophisticated "web surfer" and the reboots are not a problem for what she does.
ARM kernels likely are not facing these same issues.