A PLB is insurance when things go sideways -- a Plan B so to speak. A good plan with the relevant skills to execute will always be Plan A, but when things don’t go as planned...

I started carrying a PLB as gear on my aviation survival vest. The aircraft had an ELT but sometimes aircraft sink and there goes the ELT. I wanted to ensure an emergency beacon was with us after the aircraft was gone. I don’t fly any more, but the concept remains valid. You don’t plan to ditch, but you should still be prepared for the unplanned.