You misinterpreted the syntax of the page...
You'll notice that it starts
tar [-]{cvf...}
This means, optional dash, then come any number of options. The tar options MUST come first, and they can be preceded by a dash or not.
tar is one of the oldest things in UNIX. I'm almost certain that the funny option behavior is a consequence of the context you would find tar operating in - dumping and restoring files from tapes - and the dash was needed to allow tar to understand what kind of tape drive it was dealing with. A tar command from that day probably bore little resemblance to a standard UNIX command of today, and looked more like a TSO tape operation with explicit blocking and record layouts.