Classic: Mozilla breaks compatibility with millions of websites on the internet

And, like always, there is a relevant XKCD: http://xkcd.com/1172/

Moreover, there is no reason to use vendor-prefixed css without the soon-to-become standard css property. Bad code is bad code, Mozilla is not responsible to fix it.

The Lord giveth and the Lord taketh away. Job 1:21

It says 'Classic'. I immediately knew it wasn't something recent.

The entire point of vendor prefixes is to allow webpages to start using the feature before they are standardized in order to avoid accidental dependencies of production websites against non-final syntax: in many cases the prefixed versions end up getting standardized as-is, but that is not always the case, and just assuming "I bet the standard will be the same as what I'm currently using from this browser" is something no one should be doing. A better argument might be that "web pages should gracefully degrade, and are only using these vendor prefixes temporarily for internal testing development: people who ship production websites that rely on these features are doing something inherently wrong", but developers can't just "fall back" to the standard without doing something even worse than that.