For one thing, it's just plain eye-rollingly annoying that legions of vapid twats leave their urban habitats for just long enough to participate in a social media fad meant to show everyone how, like, TOTALLY outdoorsy they are.
For another, many fish species, aquatic insects and arthropods, and salamanders (hellbenders being the best known in this context) use stream rocks and structure as their habitats, spawning and feeding grounds, etc. So when stupid cunts move all the rocks for Instagram pictures, it kills members of these species, and harm's other species that rely on them as prey as well.
"B-BUT HIKERS HAVE BEEN STACKING ROCKS FOR YEARS!" To mark trails, yes. That just makes pointless rock-stacking for shallow clout-seeking even more annoying. It still harms the environment, especially when lots of people start doing it; and just because we used to do something doesn't mean it was ever a good idea.
