[prawn]

Not sure they did miss the point, by my reading at least. Outside of impact of vehicle traffic on animals who otherwise roam, you're talking about a very specific part of the park, not the entire park. Huge portions of it are inaccessible to tourist vehicles and seen by very few. The difference between the main areas and backcountry are significant. Both you and the grandparent had experiences that confirmed their comment - you came away very aware of the human impact on our environment.

I don't mean to discount your broader position, I just don't think you're actually arguing against your comment's parent. Yes, the parks are absolutely swamped and many will gradually bring in shuttles or lotteries and the like. Zion runs a shuttle, Bryce also. Half Dome and The Wave have lottery systems as it is. Getting a camping spot in the big name parks during peak season is miserably difficult. When I went to Rocky Mountain last year, we drove Trail Ridge Road and found a parking spot just once that allowed us to stop. Every parking spot was otherwise taken along the entire drive. And the main, named trails' trailheads fill up daily too which meant we didn't even try. But that's not the entire park. Think of it like the ocean where almost everyone plays on the beach but you have to be well-equipped, skilled and aware of risks to dive at a continental shelf or cross oceans or whatever. (Just pretend cruise ships and trawling boats don't exist for this comparison...)