While I don't think that those necessarily mean it can't work well on iPhone, it does bring up an important point about feature differences between iPad and iPh

While I don't think that those necessarily mean it can't work well on iPhone, it does bring up an important point about feature differences between iPad and iPhone, and one that Apple surely considers: They are _different_ devices, and are _different_ sizes. Some functions will work better on one device than on the other, and vice versa, because of this. This is why it makes sense that iPadOS is now a thing, and why features might exist with one and not the other. It shows that Apple is carefully designing the OS for the different devices.