Software engineers are smart people, but being smart does not exclude someone from making mistakes.
Case in point, the most recent update for WordPress (at the time of writing this post in February 2018) literally broke itself.
This article goes into more detail, but the short story is that developers releasing a standard update to the WordPress core software accidentally disabled the auto-update feature from working.
So, if you thought you were clever by enabling the auto-update feature on your WordPress site (which, by the way, only updates the core, and does not update the theme or plugins…) the most recent update to WordPress has essentially put a wrench into that clever plan, and in theory your site could have gone forever without getting any updates whatsoever.
For this and so many other reasons, it’s best to treat your site as the valuable asset that it is, and get yourself a professional developer to watch after it.
Thankfully I still update my sites manually, and I stay subscribed to 3 different security-related newsletters, so this glitch did not escape my attention, nor did it affect any of my clients who pay me for monthly maintenance. As for the clients who opted out of maintenance when given the chance… well I suppose I’ll hear from them soon when they discover their site is busted!