I'm positive that the majority of people using instagram use it FOR the filters, not for the social network. If you're a good photographer or just simply took a great photo, you don't need instagram to get it out there. I'm not bashing the service, but I am not going to defend the millions of photos on there that are a waste of time.
You are positive? How so? It sounds to me like you are just making a baseless assumption. Instagram is a good place for real photographers to show their work and to see the creative work of others and provide inspiration. It's not all about the filters.