I think gp is talking about the long-run. That is, getting things to render right on all browsers, on all devices, printed, etc.

Have you ever tried printing a thread? It's bearable, not certainly but pretty.

That's like saying you don't indent your code blocks because hitting tab is slower than not hitting tab.

The point being that there is a lot more to development than keystrokes.

But let's user your argument anyway: what's faster:

<div id="content">content</div>

or

<table id="content"><tr><td>content</td></tr></table>

Now, lets say I want to move the table text from left to right alignment. While you're mucking around in your code, I pull up the css file and add a line.