The point is perfect competition, highlight on perfect. In oil business there are profits because competition is not perfect. Note that perfect here is rather a theoretical, economic term. In reality, market regulations and peoples socio-economic attitutes prevent a perfect competition.
The mentioned missing trust could be alleviated by IPFS becoming a widely trusted, distributed, unstoppable service.
My point is exactly that if Filecoin does get to be a place that gets "perfect competition" as you say, then there is no profit to be made. If there is no profit to be made, what is the economic incentive to spend on disks/internet/computers and be a storage seller?
Before you say "there is a market for those with excess capacity", answer me this: if the market is focused on those with excess capacity, what mechanisms are in place this "perfect competition" to remove all chance of profit and get the price of excess capacity to reach basically zero?
I get IPFS, I think. I do believe that it technically it makes sense. What I don't get is Filecoin.
The mentioned missing trust could be alleviated by IPFS becoming a widely trusted, distributed, unstoppable service.