Not to mention the use of `ProxyContracts` that obfuscate changes to the actual contract implementation.
When you interact with a certain contract, you are likely interacting with the ProxyContract which relays your calls to the actual contract. The proxycontract is often under lock or has multiple signatories to amending but the "origin" contract doesn't.
So many DeFi projects get "audited by Certik" actually just get their proxy contracts audited and there is nothing in there but a single line per function, calling the origin contract.
Sorry, I thought DeFi stood for decentralized finance? Why can't we put "more complicated instruments" into wallets? Why is a bitcoin future different than a bitcoin, for these purposes?
You certainly can. DeFi typically refers to smart contract protocols for lending, borrowing, swapping, pooling, etc. DAOs also fit under the label. These are usually on the Ethereum chain because its smart contracts are considerably more powerful than Bitcoin's.