That wasn't a problem with Napster, Limewire, BitTorret, and all the other P2P apps that existed before... people will download and run things if they believe in the value of doing so.

This isn't the 90's. Downloading and installing software really isn't a thing anymore for a lot of people.

Really? App Stores seem pretty popular.

Based on the aether's name and your comment, I thought this discussion was about Ethereum.

An app built on Ethereum would also check off the 'decentralized' box for people who are angry at Ellen Pao.

https://www.ethereum.org/

To me, decentralization isn't just about avoiding control. I think that the network effects that decentralization yields are the only way to compete with an established network. It's hard to get people to agree on which centralized alternative to use, but if structured correctly, there can be just one decentralized alternative with several benevolent forks with different features, but a shared data store. No one's in control, and everybody wins.

And it is more than possible! Eris Industries inception project was effectively a reddit clone running on etherium.