They can't interfere with what you want to do. They could try to prevent you from interacting for a while but it would be futile. There are heavy disencentives, and decentralised enough. Which is why this has basically never happened. Talking strictly bitcoin and Ethereum here.

In honesty I have no experience with a pledge asset line but I can guarantee you that if the institutions involved in conducting it wanted to, they could cancel it on you anytime. With a correctly coded smart contract on Ethereum, you could ensure that never happens.

One system requires trust in third parties. One gives you the option to design a system to minimise or eliminate it.