You don’t have an account unless you activate it, but they do hold your Instagram handle if you were to sign up that would be your Threads handle. The 50% drop in activity is because the app is lame as hell, and once people saw it they were done. No chronological sorting option, not even an option to only see threads from the people you follow.
Tab folders became such a nuisance for me on Chrome Mobile I started using Firefox. I keep only 5-6 tabs open at a time, webpages opening in the same tab group thing was just too confusing for my very lean tab management mind. Now my 5 tabs really had “9 tabs”.