Because the responses are often distilled down from the same garbage Google serves up, but presented as the opinion of Claude, whom she increasingly trusts.
I use Claude a lot. I have the most expensive Claude Max subscription both for my own consultancy and at client sites, separately. I'm increasingly close to an AI maximalist on many issues, so I'm not at all against extensive use of these models.
But it's not quick enough to of its own accord resort to verifying things before giving answers to be suitable as a general purpose replacement for Google unless you specifically prompt it to search.