It's mind-boggling to me that many projects I've heard about and worked on treat (hardware) watchdogs issues as impossible to debug, for the exact reason you me

It's mind-boggling to me that many projects I've heard about and worked on treat (hardware) watchdogs issues as impossible to debug, for the exact reason you mentioned...they didn't set up a software watchdog. Doing some basic groundwork and implementing the timer/software watchdog, writing out to logs when a watchdog is about to trigger, and not disabling the watchdog during development are all basic things teams can do to more easily catch these issues before shipping firmware. JSYK: I do believe this was mentioned in the post as well, under the section 'Adding a “Software” Watchdog', but when a little bit further and implemented a per-task watchdog.