In general I think it can be fine to use a person's device for other things.
A famous example is Skype: they were able to set up a global VoIP system with very little capital, by making it a peer-to-peer application rather than requiring a central server to route all calls. So your computer was used to forward unrelated calls, but that's generally fine, the burden on each individual user is low.
In the Skype case, there were tons of computers out there, owned by individuals but mostly idle, and Skype managed to use them more productively--that is a win for everybody. With mobile phones it might be a bit different because the bandwidth is limited, but still, people can see how much data the uber app is using, and decide whether it is worth the benefit to use it to hail uber cars or not.
Skype example proves exactly the opposite: the main reason they had to switch back to a centralized setup is because as mobile became a more dominant usage scenario P2P became untenable. Supernodes had to serve quite large and -- worse -- constant traffic which kept them alive (draining battery and consuming data).
From the article, it seems this is not a true p2p architecture. It's more of a hub and spoke model, with each phone connected to the cloud, but not to other phones.
A famous example is Skype: they were able to set up a global VoIP system with very little capital, by making it a peer-to-peer application rather than requiring a central server to route all calls. So your computer was used to forward unrelated calls, but that's generally fine, the burden on each individual user is low.
In the Skype case, there were tons of computers out there, owned by individuals but mostly idle, and Skype managed to use them more productively--that is a win for everybody. With mobile phones it might be a bit different because the bandwidth is limited, but still, people can see how much data the uber app is using, and decide whether it is worth the benefit to use it to hail uber cars or not.