Ello was a network that was trying to compete in the same market segment (free social networks) with other social networks. In other words it was overlapping them and thus the networks with the bigger network effect were more relevant. Even Google is kind'a failing for the same reason with their google plus, despite pushing it down the throats of all its users.

Now, we could argue that after the introduction of steemit the market is fragmented. There was just one market with various players (fb, twitter, reddit, ello, national social networks, etc) playing in that market.

Now that market "monopoly" is broken by a new choice: Paid-Participation Social Networks. So we had one shop in town (free participation) and now we have two (free + user gets paid). When you have one shop which gets all the clients, and then another opens, the first will lose some clients and the second will see a booming growth (as it starts from zero to chew the 100% market share). Even from 0 to 1% is booming growth.

Likewise, in our case, if the unified market has like 2bn users, then if just 1% moves to Steemit due to the incentives of the "new shop", that's 20 million users right there.

When a new option is provided to the market (paid participation) and the former monopoly (give-your-content-for-free) is no more a monopoly / no longer the single option in town, there are booming-market-dynamics in terms of growth.

Now as these people come onboard, there'll be some issues in terms of scaling, in terms of retainment, in terms of usability, etc etc. And there's also the problem that the promise of paid content may not deliver because the userbase may scale x100 to reach 5mn from 50.000, but the rewards cannot follow this booming growth dynamic - and predictably will fail the audience.

At that point the maths of the model may be revisited to increase the reward structure to make it viable - at least that's my prediction.