Most Linux distributions use the DejaVu fonts by default. Browsers tend to take the default font-family from the desktop environment and thereby achieve a consistent result between web pages in a browser and documents in other applications. I as a Linux user have been reading Wikipedia pages in DejaVu for years and am very, very happy with it.
It can be assumed that Linux distributors spend reasonable efforts to make the default fonts look good. The same cannot be assumed about "unusual" settings.
I have just tested the consequences of the proposed font stacks using the following test case:
<p style='font-family: serif;'>Generic serif</p>
<p style='font-family: "Georgia", serif;'>Georgia</p>
<p style='font-family: sans-serif;'>Generic sans-serif</p>
<p style='font-family: "Helvetica Neue", "Helvetica", "Nimbus Sans L", "Arial", "Liberation Sans", sans-serif;'>Helvetica Neue and friends</p>
- The first paragraph is rendered in DejaVu Serif, as expected.
- The second paragraph is rendered in DejaVu Serif because Georgia is not and will not be installed on this system and Firefox doesn't find any substitute better than the default DejaVu Serif.
- The third paragraph is rendered in DejaVu Sans, as expected.
- The forth paragraph is rendered in the totally obscure font "TeXGyreHeros-Regular", which is neither in the stack nor my preferred desktop default font. Firefox chooses this presumably because it thinks it's in some way similar to Helvetica. It looks really, really bad, blurry, too dark and I consider this absolutely unacceptable. Note that this is what the main parts of the text will look like. I will revert this in my user.css. Others may not be able to do so.
What problem is meant to be solved by these font stacks? What has been done to verify that the desired effects and only these are achieved? What alternatives have been investigated?
Also I would like to question the explicit use of Arial in this font stack. Arial's popularity stems from it having been the default font in Microsoft products in the 1990s, but more recent Microsoft products use Calibri instead of Arial, presumably for a reason. Arial is still preferred by some because of its wide availability on old platforms like Windows XP (Calibri was first shipped with Vista), but this problem can be easily avoided by simply using
font-family:sans-serif and letting the browser do the rest.