The Maximizer really did deliver claimed performance. The problem was a really kludgy temperature-sensing sub-circuit. PWM control is now integral to most trolling motors.
I think the introduction of switchers in PC (personal computer) supplies was about in that time frame more or less.
Ayup. Aerospace was doing that in the '60s. Detroit was doing it before that,without electronics: the venerable electromechanical voltage regulator was a switcher.