Little bit related: When I come into a company as CTO, and there are too many bugs, I just close all bugs older than 6 months. Usually that's more than 10% (and the org wasn't capable or willing to fix them). Hasn't created any problems yet, but everyone feels better immediately (and we implement ways to not reach high bug levels again).
Wh... why?
Probably this. Can't fix everything, and the bugs piling up demoralizes many engineers. Six months is a bit low, I'd go higher, but there's no point having a bug on your board that you're not realistically actually going to fix.