I think they not build a social platform like steemit or facebook, instead you have to give them permission to access to ur social media, but i'm wondering how this is going to work in case fb and twitter banned their service.
That's what I thought in first ( building their own social media), but after I read their whitepaper carefully I found a section that explaining a little bit about how their service is going to work, and it turned out that they will track and analyze our socials media like twitter, facebook etc and that users will need to give them permission, is going be like when apps ask to access to personal stuff on be able to post and read message ....
I think need to add section to explain that in details, so we can understand more.
Facebook and twitter have API that allow third party to access to user data if the user give them permission, just like when you download app on play store and those apps access to your photos and camera etc..., But when those companies banned a service then it can't use their API anymore. We do that everyday when we sign up with our social media on different websites for example or download apps on playstore.