Not really an English thing so much as a math thing that makes too much sense to not use elsewhere. For instance, in math you might have x[3 - 7{3y + (a * b)}]. I haven’t actually seen them go deeper than three sets, though, so I’m not sure what would be next.
The ‘printer of fire’ error used to be a legitimate and important concern. Ye olde printers really could light their paper on fire under certain circumstances and they would typically be huge devices in dedicated rooms rather than something right next to your system. Letting people know to check on it when specific things went wrong probably saved a few buildings from burning down with people in them.