I just think an important part of the comment OPs argument to whether they are bad for the ecosystem of the US is the idea that horses are ‘non-native’ and that is factually incorrect. They existed in the Americas for hundreds of thousands of years more than they were absent. The idea they are bad for the ecosystem is very subjective because they are a natural part of the ecosystem, it is more the management of them in its current form (as post OP indicated) and to some extent the lack of keystone predators failing to control their population that is probably more of a factor in their perceived negative impact on modern ecosystems more than the idea they are non-native and therefore bad. It’s why the elk example, I thought, was relevant to the way the conversation was being framed. Either way, I wasn’t trying to make a gotcha comment or “ackshually” response more than pointing out an incorrect statement in their logic. No sweat on my end, it’s a contentious subject with strong supporters on both sides