Let's state explicitly why it's harder to base a business atop a decentralized network - because a business makes money by creating friction in the service, and in a decentralized model a friction too strong will be routed around.
Well, I think it depends on whether you are talking about decentralized networks, as I read the parent to your comment to mean, or decentralized ownership/administration of networks, as I read your comment to mean.
That is, the network can be decentralized but still administered by a single business entity, in which case you theoretically get a network more robust to outages, or the network can be composed of many separate entities, in which case you are theoretically protected from the bad behavior of any one administering entity, since there are many others (as in your example).
The other reason it may be harder to build a business atop a decentralized network is that the costs associated extra hardware, software, and locations and troubleshooting required to achieve the gains of a decentralized network may outweigh the gains achieved by doing so.
