It is already both (for the most part). The problem is that people will always prefer centralization. From shopping malls, capital cities, credit cards... to Internet platforms, the unavoidable fact is that centralization makes things easier, cheaper and more convenient.

Even federated-by-design technologies like email have slowly turned into mostly centralized services. Just having to pick an email provider is too much work for most people. Gmail is good and free, so everyone uses that. As long as servers cost money and big corps can offer free things to get user share, decentralised services are doomed to never become mainstream.