It provides information so you can make a decision. If I were to test positive based on having symptoms, I would not visit my elderly parents (or indeed anyone else), I wouldn't go to the office and would wfh (if too unwell to work as I was with Covid in Oct 21, I would take time off sick, now I'd be paid, when freelancing not), I wouldn't go out unless I really needed to. Same as if I were to have a heavy cold, flu, a dose of noro or whatever else contagious.
I've got knee surgery on Monday, I need to do an LFT on Saturday and at the crack of dawn on Monday before going to the hospital - if I test positive, my surgery will be postponed. Positive test would still have an impact on my actions and activities