I think you make a valuable point that gamifying or incentivizing sign ups would help get more sign ups. Some ways to do this effectively would be to:

Implement a referral program that benefits both the referrer and referree.

I would think to remove all automatic delegations from Steemit Inc would be a good idea to improve the quality of sign ups. Or perhaps, limiting it to a time frame of say 1 month which is enough to get some posting done and earn some SP or invest.

It would be cool if there was a newbie market which listed new accounts for others to randomly delegate to if they like their content. That would reduce dependence on Steemit Inc for new user Steem Power.

One problem is that folks don't really grasp this is a crypto wallet. It should be thought of as an investment, not employment. The way it's marketed doesn't help at all.

I suggested on another set of comments yesterday the benefit of making new account signups peer reviewed to cut down on spammer signups. Although that's only doable at the interface level. However, even the Anon faucet is an interface and lots of spammers sign up there.

In response to your article, users can sign up their friends using their own SP through Steem Connect, eSteem, the Vassel wallet, and other methods. Although usually that means your accounts are linked and that can cause some issues sometimes.

Most of the time referrals aren't considered independent accounts unless they're made through Steemit Inc or the faucet or a script on the chain everyone recognizes as being independent. Otherwise, accounts are created by you.

Each account is only a wallet. It just happens that Steemit created a social interface that interacts with Steem Blockchain wallets.

Also, the next fork makes signups very easy. But I have no idea when that is going to happen.