At the sharp end, I'd say there are such non-formalized "processes" in place. For example, market making is not really programmatic for low liquidity stuff (and no, AMMs are not good for price formation absent arbitrageurs). Dealing with sudden changes to the state of the world is another. Heck, simple price formation for shares is totally not formalized.

Also, not clear how defi would do on balance sheet money creation (at least to me) if we are replacing banks. (And what about all the other players in the financial ecosystem?)