In your example Flask would be a single point of failure and could indeed be called decentralized. For example websites can individually patch their Flask installation and come back up one by one, without depending on anyone else (at least once Flask is fixed).
Here with Cloudflare, a single entity is responsible for the fix and will more or less fix the failure for every sites that uses it at the same time, by fixing it on their side. And website individually cannot do anything on their own.
So I would argue it makes sense to call that centralized, at least from a structural/operational perspective.
It is at the very least a form of contraction of the network.
From an operational perspective it's just a supplier like any other. Lots of suppliers are involved in a business's website. That doesn't make it centralised, though?
> It is at the very least a form of contraction of the network.
I think it's that at most. No one has to use them, as they accelerate / enhance open protocols. That is the least lock-in one could hope for, so they don't contract anything in a negative way.
Contrast with, say, Etsy/Shopify, who actively try to replace the open space with closed ones.
But every word can be relative to that? I don't see where we'd go with that. I do think it's how the word relates to the topic that's interesting, if that's what you mean, but I think we are trying to get at that (-:
Here with Cloudflare, a single entity is responsible for the fix and will more or less fix the failure for every sites that uses it at the same time, by fixing it on their side. And website individually cannot do anything on their own.
So I would argue it makes sense to call that centralized, at least from a structural/operational perspective.
It is at the very least a form of contraction of the network.