Why you ask?
Admission by invite - it is an opportunity for all who are already in the network, invite those whom they want to see on Steemit.
And it will certainly not spammers, but rather their close friends and acquaintances. This is because the social network? To do so would be a logical and natural.
Now that can greatly someone does not like it, and someone really to the taste?
This is to bind the number of invites to the Volume of Steam Power.
The more Steem Power invites the more a person gets. This will allow those who have a lot invested in the development of the network and has a lot of weight to exert greater influence on the development of the community.
P.S.
English is not my native language, I apologize for best tongue-tied.