Interesting article, I echo your concerns about retaining new users. A good example of the uphill climb new users face is voting power, in particular the 15 allocated to new users. Instead of slowly diminishing as users gain their own (say -1 for every 2 gained) the power is lost as fast as it is gained - killing incentive to focus on gaining more until breaking free of the 15 cap.
In general, there's a lot of little things like that which add up over time to grind down new users. I think a bit of polish (in terms of both design and user experience) could go a long way to giving Steemit not only staying power but an accelerating growth rate.
The only way for minnows to grow is to find a community, is extremely difficult to thrive on your own.