Why they just do behaviour questions on interviews?

I just got accepted to work in cybersecurity in one of the FAANGS after an interview process of 5 rounds.

But must of the part it was behaviour questions. Just one interviewer made me technical questions. I know other people working in other companies that got offered a position as well but after several behaviours questions.

Could someone tell me why? Why is behaviour so important for this big techs, more than the technical stuff?

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