I have driven vehicles ranging from motorcycles, sports cars, station wagons and several million miles worth of big trucks. Every last one of them has had a blind spot. It is a fool that make a maneuver trusting only his mirrors.
On the motorcycles I rode, now considered vintage, the mirrors bounced to the point of not being any more than a legal appointment. We turned and looked before we moved.
I don't use a mirror on a bike because I'm gonna turn and look anyway. There's no way that I would trust a mirror to move myself and bike into what at a minimum would be 10 to 15 times bigger than me and moving two to five time faster. I'll look.
Use a mirror if you care.