> So, from those examples it looks like the real advantage of the DeFi is that is a greenfield implementation by a small team, as opposed to depending on the existing burocratic and slow banking organizations. Would you agree with that?
Partly (and not really limited to a small team, any one can join a community and contribute to a protocol or build upon it with a protocol of their own with the public abi's of the contracts), but another part missing here is that the financial system as centralized as it is, is still pretty fractured and opaque with various hidden ledgers, hidden risk management systems and hidden counter parties all over the place who don't necessarily trust one another and one doesn't really have any way to get any insight to what risk looks like overall between them (and partly because the entities want to capture the value by being in between the users) from the perspective of the public.
> regulators off your back and banks to cooperate,
It's more than about just regulators, its about users having a say over how every actor can engage with a system. If one address starts making transactions that abuse its position with a protocol (via governance or excessive risk taking within the protocol), users can fork the code, make needed changes to mitigate against such, and withdraw their capital from one protocol and use another easily with the new changes. The users themselves can capture the value while also using the system.
> what would you choose? Centralized or blockchain based?
With permissionless DLTs, you can see credit build up in real time with all counter parties involved with a protocol in a way you cannot with the existing financial system without the need for regulations, that __may__ serve, at best in the short/medium and long term interest of users/counterparties (most of the time, regulations end up really only enabling incumbents to come up with better ways to hide how risk builds up while stifling other competitors out of the market, even if initially they end up making things transparent for some aspects of the financial system). And because of the lack of trust upfront, most user will not want to use a protocol that does not open source/verify its contracts on chain.
With centralized systems in jurisdictions with lesser regulations (i.e caymans, bahamas, etc), the opposite is the case where you have even more opacity into operations and very little incentive to be open about it with ones users or counter parties (think something like FRAX/DAI/FEI [where one can see collateralization in real time on chain with the various assets and the leverage] vs USDT/USDC [one has to trust them at their word or spend resources threatening legal action that may at best on show a snapshot of what constitutes is collateral at any given time, and they have no incentive to share their code for how the manage their operations and risk]).
In a perfect world, where everyone could trust each other (and the banks) to be open and honest all the time with their dealings while allowing for some semblance of psuedoanonymity for those who want it, allow potentially anyone to use such even if some individuals may not like another for whatever reasons that have nothing to do with the system of transaction themselves, write code and systems that are interoperable and easy to build on by others, I would prefer centralized. But that world is a pipe dream.