User blog comment:DaNASCAT/Technical Update: March 17, 2015/@comment-1251315-20150318113811/@comment-1251315-20150319180312

@Kirkburn: But I don't like syntax highlighting at all, I don't want to see the text being highlighted at all on any wiki I edit. I just want a purely text-based source mode with no fancy features, I don't need things highlighted to me because I'm quite experienced with all forms of syntax on MediaWiki. If I wanted syntax highlighting, I'd use VisualEditor but I hate such things.

The setting says "Do not show syntax highlighting in Source mode". That means do not highlight ANY syntax on any page in Source Mode, not do not highlight wikitext syntax (but JS/CSS will be left as it is).

I share 452's sentiments: I use Common.css because the Special:CSS is very irritating to deal with on dark wiki's (you can't read anything) and the colours just make it look like I'm looking at a bowl of sick that someone just vomited into (literally).

The option is quite clear on what it should be doing, but the fact it doesn't disable on JS/CSS means I cannot edit my JS/CSS files whatsoever which is VERY misleading and annoying, not to mention very inconsistent.