It lacks context. Search engines spews a lot of garbage, because there is a lot of garbage in internet, and SEO put some weight on garbage too. But devoid of any context you won't have any hint to decide that what the LLM is throwing out is garbage or not, as you might or not have with a random search engine result.

In any case, LLMs feeded with carefully curated content instead of random pages or social networks posts (maybe upvoted because funny instead of accurate) may have better chances of giving out good results.