Tools like Playwright and Puppeteer are abstractions on top of CDP. The other use case is when these frameworks don’t expose or don’t use a CDP command you need (often they hide some parameters for cross browser compatibility).
Webdriver BiDi is a future cross browser replacement:
Bidi’s not a viable replacement for some use-cases e.g. setting headers for just the main origin as it’s add header command adds the header to all requests potentially causing CORS issues
Webdriver BiDi is a future cross browser replacement:
https://www.w3.org/TR/webdriver-bidi/