Um, they have to run a lookup to find the 'value' for the given 'key' regardless...? I cannot think of any positive value for the user here -- it's non-standar

Um, they have to run a lookup to find the 'value' for the given 'key' regardless...? I cannot think of any positive value for the user here -- it's non-standard & slower. 3XX redirects have been around a long time and basically every single client out there knows how to use them, and those that don't can look the status codes up to see how they should handle them if they want to. AFAICT this is purely to allow for the 'pseudo injection' of the third-party JS, presumably for tracking purposes... Only question I'd have is why they can't read the cookie server-side instead, but I'm guessing there are cookies on other domains that their JS is looking for? Haven't done web stuff in a few years so I'm behind on CORS-ish pros/cons/knowledge.