Ryan's excellent patch that prefers F/OSS fonts is merged, you can try it on beta labs while it rides the 1.23wmf18 train. I updated the Typography refresh page to reflect this.

 

Isarra Yos asked:

Has it ever been specified why mw needs a font stack in the first place?

The Goals section of the Typography refresh page is incomplete, it's missing a fundamental:

  Because designers:  improve the appearance of the fucking site.

"mw" may not need a font stack at all, maybe "the site" here is only WMF properties. Steven Walling, could you clarify the goal? As Jon Robson pointed out earlier in this thread, WMF can have settings to only apply the font choice to Wikimedia projects.

When and if the typography update moves out of Beta feature and into the Vector skin, MediaWiki could go out with straight serif headers and sans-serif body, while WMF sites get the carefully-deliberated font stacks.