For a lot of people, the only ADN functionality they really care about is that which replicates Twitter. How do you provide a free tier to these people that doesn't remove any incentive to go paid? Limiting the number of people you can follow seems like a great way to do this.
I'm interested to see what uses people come up with for ADN's storage. If there are some neat uses, that could be a great incentive.
I don't disagree with the limit providing a great incentive to go paid, but when a free user joins, there is a point where the user decides this service is neat/useful enough that he wants to pay for it. I wonder if this limit might hinder people reaching that point.