Honestly the landing strip theory is basically a meme at this point but I refuse to fully bin it just because Erich von Däniken became everyone's favourite punchline. The lines are unnervingly precise for a culture working without aerial views, and that bugs me more than I'm comfortable admitting.
That said the ritualistic/astronomical angle does hold up better under scrutiny, like the whole "walking the lines as a ceremony" idea makes more sense than ancient runways that somehow got buried under centuries of nobody noticing the massive aircraft parked nearby.
What I always come back to though is who are we to say definitively what they were for when we still dont fully understand the civilisation that made them. Anyone here dug into the water/irrigation theory? Feels like that one gets criminally underreported next to the alien stuff. Would love to know what others reckon.