It's not a utopia ...it is possible ... how did yahoo,google,facebook start ?... and look at them now ... they built their platforms the same way i wanted to ... step by step ...problem is people lost fate in the internet ,and the internet did gave them some very good reasons to lose fate in it ...
Now people think that the giants like google,microsoft etc have the solutions to all the problems.... not true ... we are still out there the rest of us and we see the problems that are still not solved yet ...
In theory, everything is possible. Here though you propose something that needs a lot more than a site/ platform and the most "crucial" point of it is the consent/ permit from already big companies/ brands. You compare Google, Yahoo, FB, companies that are not even related to the project that you propose. Even if we try to compare them, you forget something important which is the time period/ frame. They started the right moment at the right point...