You can put ferrules on stranded cables like flex where the copper is made up of lots of thin strands. The thin strands are easily damaged when you’re tightening a terminal screw so by adding a ferrule you get a more mechanically durable connection that provides a better electrical connection too.
Hmmmm... I'm pretty much sold.
On the review I watched they put a ferrule on and crimped.
Why?
https://youtu.be/D7sRVMKu5Mo
(1.45)