ყველა პროდუქტი ერთობის განხილვა

I have noticed that mobile browsers (including Firefox Mobile) don't seem to give you the option to clear cookies and other website data on close while preserving website info/cookies of sites you want to keep logged into.

Is this a feature that will eventually be implemented in Firefox? Or is there some kind of limitation in Android/iOS that makes implementing this not possible or tricky?