At least it's WebKit and not just a reskin of Chrome, but I don't exactly get why Kagi feel that they need to develop their own browser. Personally I prefer my search and browser to be developed be separate entities that can focus on doing one thing really well.

Yes, and you need an army of people to "wrap" WebKit just like that. E.g., the WebKit port on Haiku, of course, is not in good shape because it has more code than the whole of their OS. EFL once had a WebBrowser control/component, maintained by Tizen devs, but of course, it has now been removed. There is no manpower to maintain such control.