Indeed,
harm reduction is about efficacy (effective, safer alternative one doesn't need to over-use) and that includes satation - which needs include a 'hit'; as you said, even the WTA if weakened sufficientlt by a bad
device will not create that impact + satiation.
Ride a roller and the buxx lasts. Imagine riding it at 1/4 speed. Would going around for 4x as long be as good? Or even 10x ?