That really only applies to moderate traffic area.
Gates of the Arctic National Park and Preserve sees ~10,000 people per year and covers 8,472,506 acres. At the other end Grand Canyon National Park sees ~4.5 million visitors there’s a world of difference between them.
But even the Grand Canyon National Park has 1,217,262 acres the majority of which is seeing below 1 person per year. It’s hard to track someone walking through an area after even just a week, the actual impact from an individual visit is tiny, it’s only at scale that there’s issues.
Delicate plants taking years to recover isn’t an issue when a random square foot is unlikely to see 2 visitors in 1,000 years on average.
It just doesn't work that way. If you consider the small percentage of acres that are actually walkable by humans and how humans would get to those areas from feeder trails, then the impact isn't just a random person walking in a random square foot in the entire park. Humans don't just teleport to random square foot patches. They get there from feeder trails and are constrained by what is traversable in the first place. And who gets to choose who walks off path? Everyone gets to? Only certain people? I'm not sure why you're arguing this. It's been studied, and it's damaging. Going off trail also increases the chances of introducing non-native plant and insect species.
Nature isn't for us. The trails are enough to experience it. Going off trail is selfish and damaging.
* Off-Trail Trampling Has Lasting Impacts: https://daily.jstor.org/off-trail-trampling-has-lasting-impa...
* Going off trails: How dispersed visitor use affects alpine vegetation: https://www.sciencedirect.com/science/article/abs/pii/S03014...
* Off-trail trampling causes millions in damage to national parks: https://magazine.washington.edu/feature/off-trail-trampling-...