When I'm raiding...
When I'm raiding a tomb of a lost civilization, I can't be worrying about whether or not you're playing with yourself.
So, yes: the magical, inescapable chastity cage is necessary. The spikes are just for fun, though.
A loose tie-in with my erotic femdom chastity novella, Treasures of the Flesh, available on Kindle. https://www.amazon.com/dp/B07JDDFZQZ