That's a good point! I think the RC situation relaxed a bit with the latest changes a few days back, but 15 SP still seems to be required to be able to make at least a few comments per day. Steemit is currently also giving out 15 SP delegations with new accounts. Dapps getting delegations from Steemit only helps indirectly, since they can't re-delegate the Steemit stake for own signups - this had to come from their own stake.