"The internet seems to be unanimous on openers lasting 10-15 years, so I can see the logic of replacing the opener itself."
My guess is that the beefier the unit, generally the longer it will last, especially if it's over capacity for the size of door you're opening due to less strain on the components.
But, that's just a theory.
I've never had a garage that required an opener, and when I was a kid I was the automatic opener for my Grandparent's garage door...
Friend of mine has 3 garage doors on 2 garages. Doesn't have an opener on any of them, but doesn't really need them as he doesn't park in the garages.