Really? Are you being deliberately obtuse? For someone that has not been active at all and is looking to see what kind of activity effort brings them to a desired activity target, then taking notes of what you've done and what was achieved is useful info. "How often do I need to do _______ to achieve my goal of _______" If you thought you needed to plan 1 hour per day, but realize you only need 15 mins per day, that's useful. NOBODY is going to count their steps manually.

Personally seeing that I've done way too little steps/exercise reminds me and motivates me to be more active. If you are always equally active no matter what then yeah it's just not for you but not everyone is you.

It helps me realize I haven't stood up in the last 4 hours and I should probably walk around more this afternoon.

point in time data doesn't really help as you mentioned. But if one can segment this and compare and contrast with other cohorts there could be other items that could be work taking some action on.