What is a permissionless technology
Here you are, 3 links for a better understanding.

Jared Tate - censorship and the need for blockchain technology:
https://cryptoglobalist.com/2018/09/24/digibyte-dgb-jared-is-right-about-censorship-and-the-need-for-blockchain-technology/

Josiah Spackman - DigiByte is permission-less :
https://youtu.be/WgFKZ7kf7lQ

and the best and deep explanation,
Andreas Antonopoulos: The Courage to Innovate Without Permission
https://youtu.be/ywq6NBETUJ8?t=287
All his conferences are a must watch !