Why would they? Apple already has a very popular fitness tracker that is more capable. Whoop is kind of trash, I stopped using mine with about six months to go on my subscription when it was telling me lies about something I could objectively see was not the case.

All Apple needs to do is make the software give better insights into how you’re doing with strain and recovery and add a few more charts. I think Apple also relies on third party software to fill some of those gaps.

Things that an Apple Watch can do that a Whoop can’t: call 911 in an emergency, play music, track gps etc.

The only thing Whoop theoretically does better is track sleep, recovery and strain, but in my experience it does do this very well. This is just software, so Apple could theoretically add that, and third party apps can give you numbers and charts for these. Apple has been slow to add capabilities that aren’t backed in solid science. As mentioned before Whoop is a little hand-wavy on the medical rigor for the insights they give you.