Every political system forgets its lessons (inflation, war, disease, food, housing, wealth inequality) until reality eventually slaps it in its face again.

Sure, but time scales matter. Both sides (there will always be 2 under our structure) will inevitably forget how much voters absolutely hate inflation; that's how we get inflation. But it won't happen within the lifespan of the "MMT" fad; I think that lifespan may have already elapsed.