[gilini]

The problem is not whether a validator spits several errors or not, HTML validators are tools designed to point out stuff that is not conforming to the specs. It's stuff that you should avoid, not that will necessarily break your application on any web browser.

Why should you avoid it? Because, basically, if it's explicitly forbidden, or not covered by spec, you can't be sure of what will happen in all (or newer) browser implementations. If there's no defined behavior for some code, any behavior is correct.

Also, it's not like you have to go an extra mile in order to follow the specs here.