It’s kinda interesting. If the new gambit horde mode didn’t require higher light level for the higher tiers, there’d literally be zero point in even getting your light level higher. It doesn’t help you against players outside of a week long game mode that happens seldom (which is in itself weird people it’s a primarily PVE level of power) and we’ve all been thrashing all the raids at 650. So the only thing light level does is make it take longer to do the new gambit. That’s it.