Beaniebabies were effectively regulated and taxed like commodities. Commodities do not require a real-world use. All they are are tradable non-currency things which can result in capital gains.

The speculative (HODL!!) cryptocurrencies should probably be treated like commodities, and regulated as such by the CFTC. The cryptocurrencies that are actually being used like currencies (e.g. actually used to buy things) should be regulated like foreign currencies, which would also be regulated by the CFTC (this is essentially the same exact thing as Commodities trading, but with simpler accounting rules which reflect the much higher liquidity, divisibility, and likelyhood that a unit changes hands). Neither of these scenarios involve the SEC. The SEC should only be involved when coins are being issued like securities (e.g. as a way to raise funding and sell financial stakes in some kind of enterprise).