What they should have done was add a notification in the error log when you startup-- "Query Cache is enabled. Are you really sure you want to do that? Read http://whatever/qcisawful.html for more information."
And this should have been added to the final releases of every version all the way back to 5.0.
For people saying "please, it's been off since 5.6 in 2013", my company's primary product runs on Percona 5.5 (2010), and our secondary product, is actively developing the _next_ version on Percona 5.6. That isn't particularly unusual.
> The query cache has been disabled-by-default since MySQL 5.6 (2013)