i think that for some reason, DSBs have become synonymous with "no maintenance needed"... i don't know how that happened, but it's not true. you need to change your sand, just like you need to change your water.
DSBs left untouched for years can definitely be a cause of OTS... but there's an easy way around that... every 2 years, just replace your dsb... keep a few cups and whatever larger critters you can sift out to reseed the new sand bed... but in the grand scheme of things, it's not that hard to do, and i think... plus... every 2 years is a great time for a tank overhaul, and we all know we can't leave stuff alone that long anyway.
my new nano i'm setting up is going to have a 20G display with a thin layer of sand, and a DSB in the refugium... then you have the best of both worlds.