People say this because it is true for the most part.
No, it's not. The point of validating is to ensure your code is semantic and being written properly for the doctype you are using. If you are not doing it correctly, your site will not validate. Invalid code results in your browser throwing your site into "quirks" mode, which means your broser will try to *guess* what it is you're trying to do with your site. Sometimes it's right. Most times it's wrong, and causes our site to look weird. Again, *anything* not valid will case this to happen.
There are plenty of other sites with more errors than I have that display relatively the same in all browsers.
They're either damn lucky, or their site's code/CSS is hacked to hell and back - which is a band-aid solution. Go back to the cliche: if everyone else jumped off the Brooklyn Bridge...
it just seems that validating the little things will not make a significant change when <i>my</i> problem is not with the site displaying oddly, rather the content does not display at all.
How do you know? That's another thing that gets me. Validating is so freaking *easy* it's unreal how many people try to avoid it. You start with the first thing in the list, and many times, the next 50 things correct *theselves*. I don'tthink you're taking the easy way out in not validation - I think you're making things way too hard on yourself.
What difference would it make if you attempted to validate the site piece by piece?
HUGE difference. PHP includes bring in certain pieces one after another. You could validate each section, but much of the stuff that'scoming in won't even be looed at if you do it piece by piece, because all of the info isn't being run through the validator. For example, your links list - it's a PHP include. If you just validate the sidebar, all you're validating are th DIV tags - nothing else, because the validator won't see it. You have to do the page *as a whole* to be sure everything is validating correctly, because that's the only way the validator will see *everything*.
That way you can isolate the problem better. Since when you validate the whole page it renders ALL of the includes, all it is doing is condensing all of the errors into one file anyway.
No, it's not. If you only do ine at a time, it'll never render the parts correctly, because the validator does HTML - NOT PHP. PHP is invisiable - only the output is visible to the validator. If you do i piece by piece, you are NOT getting the whole picture at all.
That should be "themes" - with an "s". You should also use the PHP code to link to your stylesheet - not hard code it in. (And full paths to your images in your stylesheet as well.)
I'm looking at the site now, and you have two doctypes in your header - I'm sure that shows up in the validator.