It appears some philosophy came along and blurred things up a bit.
So, my point is, that for a thing like this:
to be looked upon as stupid and wrong, you only need to take a look at what the specs are saying:
[URL=“http://www.w3.org/TR/html401/sgml/dtd.html”]
<!--================== HTML content models ===============================-->
<!--
[COLOR="red"]HTML has two basic content models[/COLOR]:
[COLOR="Red"]%inline;[/COLOR] character level elements and text strings
[COLOR="Red"]%block;[/COLOR] block-like elements e.g. paragraphs and lists
-->
This defines a general visual style, w/o being specific as to how font, colour, whitespace should look and measure up. But it does imply a certain visual style that, I think, it’s pretty clear to everyone.
This is where most people seem to mix-up: between default style apparent from specs and some commonly agreed upon specific default stylesheet: 16px, blue text for links, etcetera.
Inline and block have nothing to do with Firefox’s html.css. Furthermore, the way firefox&opera treat unknown elements is not to be regarded as a hint towards demonstrating a general rule, a wrong one nonetheless.
Yes, you can temper with UAs modularization by hidding html.css. That only proves that you know how to cause a malfunction
Yes, you can alter html.css. That only proves a feature, a technical one
Yes, you can make an external css stylesheet and rule all html elements be displayed inline. That doesn’t mean all html elements are basically inline, it only demonstrates you have freedom in coding