This may have use in defining standards. You could have a standards authority without any actual standards body. Free but standard.
In the case of self-hosted Apps (ie. where you need to "install" something on your phone or computer), each peer provides their own compute/storage/networking to host their own usage of the App, plus a small fragment of everyone else's usage (proportional to a few average user's worth).
So, the cost to each user is a small constant C times the average user's utilization. And the benefit is that the application persists, in its entirety, as long as any number of users >= 1 continue to use the App.
I feel like the tools available for this purpose would need to be more powerful than existing IDE systems in order for it to be adopted on a wide scale.
Is it possible to design such a system without a blockchain?
For next-gen "DeFi" systems like Holochain -- the incremental cost of executing functionality is vanishingly small, and can be distributed across a DHT substrate hosted by all users of the App.
A self hosted Holochain "DeFi" app costs a small constant factor C times the average agent's memory / network / storage cost, to each client.
In other words, you gain the benefit of the "DeFi" version of App for yourself, by investing a small C x your own cost to run the App for yourself, alone.