Yeah, they probably aren't doing (most of) these now, but it doesn't take much mental energy to extrapolate once you factor nearly every other tech company's ethical trajectory and the current geopolitical environment. Substituting classic search entirely with LLMs is not a savvy move.
A search engine could certainly tamper with which of these sources they surface/rank higher (which I suspect happening more often of late), but they're still obliged by their nature to branch out and seek information from the broader world.
LLMs, on the other hand, are self-contained opaque monoliths that can be conditioned to deceive or obfuscate with devious cleverness, and all control over their behaviors is entirely concentrated in the hands of whatever corporation trains them.
As soon as one gets annoying, expensive, advertiser heavy etc. you just rip it out and replace it with the other one. AFAICT there is zero lock-in or moat. I often am able to switch models in one click or command. This is why all the LLM providers are desperate for a product layer/comprehensive tool set.
Sure maybe they all end up that way, but there’s plenty of reasons corporate customers will want private LLM usage that is not skewed towards advertising. I am happy to pay for that.
Also, open source models are a bulwark against another search style ad Monopoly.