I think spurs should maybe be legal because you have no choice but to remove them on each use. I also feel like, compared to a drilled-type hole such as bolts or steps that would get removed leaving “gaping” hollows, you’re doing much less long-term damage to the tree with lower-profile, less intrusive piercings into the bark and cambium. Sticks, straps, platforms, climbers, ladders, and even ropes can damage the tree by girdling or removing too much bark and scarring, cutting into the cambium, and I’m sure ways I hadn’t considered as well, but these aren’t (to my limited knowledge) as immediately damaging or accessible to infestation or disease or rot as the holes left by a 3/8-1/2” bit, 2-3” deep into the trunk. If you think about it this way, to reach the vitals of a human with a stabbing implement, you need 2.5-3” or better penetration. Sure, a tree has bark, but once you pass that bark logic would suggest that 2-3” is plenty to cause damage to the tree’s “vitals” and allow other issues to get in. I think on private land you should be allowed to use whatever you want to get up that tree, and I even think the tree’s better off if you leave screw-ins/bolts in the trunk and maybe back them out a revolution every two seasons. That said, on public I think spurs would be a good non-intrusive compromise for dudes who just wanna get hunting with as little BS as possible in the kit.