But the entire premise of decentralized finance is to have no central authority, is it not?
I'm not aware of any court that would, for example, jail a Chinese citizen who stole virtual money of a US citizen? Are you?
Decentralized systems have different benefits for different people. For instance, some people like to trade 24 hours without corporate middlemen stopping you from trading at night. That's not the same as avoiding legal authority.
Ideally governance would also be done in a decentralized manner, but we’re not there yet.