Well, that is no flaw, it's your responsibility. If you lost private keys for your BTC wallet, you cannot use your BTC anymore . With other crypto it is similar so it's not hostage holding - it's more like you put your money into secure box that no one else can open and forgot the combination. However STEEM has some account recovery feature, check https://steemit.com/steemit/@whatissteem/how-i-recovered-my-steem-account-with-recover-account-option