I'd consider a browser buggy if it showed me the tags at all.
I suspect that dragonchild was speaking loosely when he said, "if it displayed h3 tags as bigger than h1 tags." It seems likely that he meant the content of those tags.
Neither tags, nor elements are commands or request. They are just that, structural parts of a document. They just exist, they do not act.
In other words, HTML is declarative rather than imperative. As the wikipedia entry on declarative programming languages states though:
The distinctions are never sharp; any computer language has an element of initializing a process in a computer, in order to be of any use.
So, again, the distinctions are really only useful from a technical vantage point. As far as legal arguments go, this won't buy anything.
"My two cents aren't worth a dime.";