This is the clash of 2 paradigms: the one in which the user signs up for an account in a centralized entity and the one in which the user signs up for an account in a decentralized entity.

In the first case (Facebook, Twitter) the cost of acquisition is assumed by the platform owner, because the user is also the merchandise that gets sold. Also, there is no control that the user can exert in a centralized organization. So you will get a tons of incentives to join, because without you the platform itself has no business.

In the second case (Steemit) the user pays for being part of a decentralized organization, thus owning a stake in it and being part of the governance. This cost was supported by Steemit INC since the beginning, and it's still supported by it. But if we expect the kind of growth Reddit has, we need a different mechanism, simply because Steemit will run out of tokens to spend for users, hence, the mining workaround: you will be able to mine an account, starting with hardfork 20. The way Steem works as a blockchain, requires a specific Proof of Something in order to prevent abuse (it's a thing involving the concept of "bandwidth").

So, in a decentralized organization, where the user has control over his privacy and is part of the governance mechanism extra steps must be taken to ensure the fabric is solid and it doesn't allow for boo-boos. I salute this conversation and all the steps taken to prevent abuse.