According to
https://www.mediawiki.org/wiki/Typography_refresh/Font_choice#Body_font_eval...
sans scores 0 out of 10 points for "readability, neutrality, and "authority" (does the font look like it conveys reliable information)." Apparently the font is not readable, neutral or authoritive at all, and completely unsuitable for the website. If it is in fact almost completely unreadable it seems reasonable to override it, even if it is
the
system default, but I have the feeling that there may be some hyperbole in that table. That said, with https://bugzilla.wikimedia.org/show_bug.cgi?id=61470 it seems a terrible idea to have Helvetica Neue in the font stack.
Really a 0? What would comic sans get?
--bawolff