In fact, Kagi benefits enormously from being small enough that no one is SEOing for them. Google's adversarial game of algorithmic whack-a-mole is very expensive and hard to keep up. Kagi doesn't have to play the game because they're not a target.
That’s a great argument for decentralization of search engine usage. The more small players with different ranking algorithms we have, the harder it is for SEO to work.