There was a bit of a mixup; In general cryptos can operate in a decentralized way, they aren't connected to anything like with Steem, where value is at least in part derived from interaction with the platform.
That could be a nitpicking distinction.
The reality of the way blockchains are operating now is far closer to the operation of a ponzi scheme than anything else (regardless of steem), consider, anyone could create a block chain. They convince others to invest, which gives the blockchain SOME value, and the increase in value only comes in from increasing people being convinced to invest so that they gain value in the coin from future investors. Whether that be investment of time, machinery or funding into the crypto 'markets'.