Tippet material is subjected to higher quality control for consistency than most mono intended for conventional tackle. IGFA tippet is guaranteed not to exceed the rated strength--records are not broken by tippet that breaks the rules, or the submission has to compete at the next higher pound test level. "Standard" tippet puts a premium on accurate diameter, and accurate breaking strength is not the priority. If you're not interested in breaking IGFA records, there's no reason why you can't use any tippet that you like. If you find mono that you're satisfied with the consistency of (or just don't fish small flies enough to care about presentation) that will work fine too.
CC