Browser as sole source of truth
The browser is the only real source of truth for page state; automation frameworks that maintain local mirrors risk acting on stale state, especially over remote connections.
Supporting evidence
Introducing Stagehand v4: The SDK for browser agents.
Original excerpt
The browser is the only real source of truth. Every framework that hands you a page object is betting that it can keep a local copy accurate and fast enough to be worth the usability. The bet is usually good enough . When it isn’t, your script acts on a page that has already moved on, and you get an error describing a browser that no longer exists.