I don't disagree with what you're saying but I'd like to offer two "counterpoints" (I don't see this as a debate but I don't know a more fitting term)

• Theoretically, a lot of web services are owned by companies that fold, it has happened many times in the past and will many times in the future. Centralizing through a business brings more stability since there is a more clear monetary incentive and companies are generally legally forbidden from just taking the money and running but it has happened.
• This reminds me of the earlier days of the internet when a lot of the content was self-hosted and could vanish as soon as the owner discontinued its operation for whatever reason. I think that as this matures we'll see more non-profits and companies enter the space which might bring a bit of stability.

I really hope that this won't all just fold in on itself after the hype starts to wane, and I personally don't think it will (aside from a period of turbulence) but I have been wrong before.