It's also marketing that their AI is hilariously terrible because AI Overview is the biggest posterchild for AI slop and often used as an example of how bad Google is at AI. Gemini proper isn't that bad, just the ultra cost cutting version on search is.
To be fair the search version of Gemini is nowhere near as bad as it used to be. The bar is in the floor I know.
It has gotten a lot better and it's useful for information on most normal search queries now.