Why don't other companies have in body stabilization (Nikon answer here)

From https://nikoneurope-en.custhelp.com/app/answers/detail/a_id/23997/session/L3RpbWUvMTMxMDM4MzY2Mi9zaWQvUlV6Y3ZJeWs%3D

1. Corrected finder image makes photo composition easy.

Because camera movement is compensated within the lens in use, you can see a clear finder image. This makes it easier to capture your subject in the focus frame and confirm composition. With a camera that corrects image blur inside the camera body, the image in the finder remains blurred.

2. Each lens is optimally tuned to achieve reliable correction.

Unlike cameras that only provide an internal image-blur function, every lens is optimised. As a result, you can shoot at shutter speeds up to three or four stops slower than would otherwise be possible.

3. Image information captured by the AF and metering sensors is corrected with in-lens VR.

This is a major difference from the in-camera VR. The result is faster and more accurate autofocusing and exposure metering.

4. Patterns of image blur are not the same with all lenses.

Image blur caused by camera movement differs with each lens used. This phenomenon is more noticeable when you use a lens with a longer focal length. So each lens should be finely tuned.

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