Some crypto's might be, if they are tied to a company behind it. Like Ripple's logo is probably copyright protected. Not sure if anybody owns the Bitcoin logo per se, but perhaps some specific stylized forms of it are copyrighted.. dunno.

Turn the question around though... Since the blockchain is permanent and immutable, does posting something on Steemit count as proof that you own the copyright over something (just like mailing a copy to yourself is supposed to be proof of authorship in the court of law)