Websites don't matter. Valuable data is what matters. The problem is that data is most valuable to a website when it is locked up and meted out in miserly portions, but its value to customers and users increases when it is open and available to use and mix with other sources. There's a tension. The database owners need to appear to be open and generous with their data, to attract users, but need to hold it back just enough so that it retains its value to them. In other words, data only matters to website owners to the extent that it draws you to their website as a user to generate revenue, but websites only matter to you as a user to the extent that they give you access to the data you want. We don't care where data came from as long as it is easy to use and valuable to us. Website owners don't care what data we are using as long as we come to them to get it. As long as that fundamental tension exists, the internet will always be a disjointed library of isolated websites, and we will be forced to use it in awkward, difficult ways.
Mokalus of Borg
PS - The tension is eased if one company controls all the data.
PPS - But that makes them a monopoly, which is bad in another way.