I ran rules light campaigns a lot back in the day. Didn't call it that. But it was the typical way it would go. We'd start out the campaign in AD&D or Traveller or whatever, and eventually it would evolve into a storytelling RPG of our own on-the-fly creation, with no formal rules besides what seemed useful at any given moment. We'd go sessions without rolling any dice.
But, that was a tightly-knit group of teenagers who'd played together a lot and who trusted each other.
In most cases, using something like
Lasers and Feelings is probably a better choice. It's an elegant game that works well and can be adapted to most genres, if you're looking for a rules light system.