Nearly every single time I recommend cleaning up the code on a website, the response I get back is: “But Why? I hear it doesn’t matter.”
My question is, where did you hear this? From someone who writes sloppy code, perhaps?
It is easier to write invalid code – that’s all it has going for it. The average WYSIWYG editor makes such websites at a mile a minute. (What You See Is What You Get – Programs like Dreamweaver, which are used to build websites visually but do not require that you look at the code to do so.) Even if they are invalid in code, these sites look pretty and that is all that usually matters to people. Standards seem pesky to deal with when you can build a site which gives every appearance (visually) of being fine, despite the messy code.