Why do they tie their thumbs and don't use handcuffs?

Question

I've seen lots of animes where a character is caught and interrogated by some authority. The captive is usually depicted sitting on the chair in the interrogation room. But instead of being handcuffed, their thumbs are tied with a zip tie.

Why? Is there a meaning? It's so weird! Is it common to use zip ties to restrain criminals in Japan? I'm confused.

No this is not some kinky anime; I don't watch that stuff, it's an action based anime, more specifically, AICO incarnation or something like that.

Answer 1

"A normal zip or cable tie is borrowed. A participant firmly cables the performers two thumbs together, making it impossible for the performer's hands to separate" (wonderwizards.com).

So my understanding is that by pinning the thumbs together, separating the hands becomes impossible and thus, minimal hand movements restrict leverage to pull on the rest of the bindings

https://www.wonderwizards.com/lesson/blacktie2018