Many human activities cause climate change. LLMs are a relatively new one, and a disproportionate energy user, so it's fair enough to shout about it and try to minimise adoption. Things that are already entrenched like consumer culture or aviation will be harder and slower to undo.

Also, whether it's right or not that capitalism is largely to blame, if you take that to mean that the only useful action against climate change is fighting against capitalism, or let yourself feel like you've 'done your part' by having anticapitalist opinions, I think that's counterproductive.