That would have devastating consequences in the pre-LLM era, yes. What is less obvious is whether it'll be an advantage or disadvantage going forward. It is like observing that cars will make people fat and lazy and have devastating consequences on health outcomes - that is exactly what happened but the net impact was still positive because cars boost wealth, lifestyles and access to healthcare so much that the net impact is probably positive even if people get less exercise.

It is unclear that a human thinking about things is going to be an advantage in 10, 20 years. Might be, might not be. In 50 years people will probably be outraged if a human makes an important decision without deferring to an LLM's opinion. I'm quite excited that we seem to be building scaleable superintelligences that can patiently and empathetically explain why people are making stupid political choices and what policy prescriptions would actually get a good outcome based on reading all the available statistical and theoretical literature. Screw people primarily thinking for themselves on that topic, the public has no idea.