If I was to give you my high level concerns:

* I would be concerned about platform dependency. These platforms can change behavior and pricing like Twitter. 

* You might be at risk of becoming a feature rather than a product. You're doing the data processing that these platforms should and probably are already doing. If they start sharing that information as metadata or through separate apis thats a problem. 

* The volume of data is tremendous and computing costs to keep up with it will be significant

But I might be wrong, fuck me!