That was my first thought when I read "guys I've been riding with for decades" too.
I know with my concussion I'm mentally not the rider I was just a year ago and I'll be riding like a granny this season

I don't think manufacturers should add turn signals that automatically cancel to make up for my shortcomings.
I think pushing for manufacturers to do that is how we train new riders to be dependent on the bike to do more of the work, rather than training new riders to always be considering what their bike is doing.