This isn't the first generation to live in a "corporate pseudo-cultural production" world.
Movies and movie conventions. Baseball cards and other popular collectibles. Sport events. Music events. All those things are just "corporate pseudo-cultural productions". Yet they're also the culture, because - for better or worse - commerce is part of our lives too.
I think saying that "finstas" are as important to society as the "web" is a false equivalence. As evidence I would point to the fact that "finstas" are in fact just a very tiny subset of the web.