You doodle away at the your Cisco IOS router and stack up the commands. You change this, that and something else. You are confident thatyou can always reload the router to get back to the original configuration.
It’s fine until your fingers type “copy run flash” because it’s a habit. You do it all the time to save your work.
dammit, no I can’t rollback IOS because it DOESN”T HAVE A ROLLBACK CAPABILITY!!!!!
Cisco IOS – limited in features, expensive like drugs. And you are stuck with cheap drugs at that.