-you can turn it off globally in settings

-some people use it docked

-if it wasn't available, someone else would be complaining about that

As the sibling says you can turn it off, but even the non-windowed UI is still not well-adapted to the small form factor. Apple doesn’t put any work into it. One can hope that some improvements might carry over from the upcoming foldable iPhone, whose inner display will only be slightly smaller, but I’m not holding my breath.