When I bought my 4-150, I was told it would never work on a H body because H bodies are not able to control or take advantage of the features of the 4-150. That is, the H bodies don't have the required smarts or connections for the features of the new back.
I'm assuming that a more detailed explanation wasn't offered due to the fact that this is complete nonsense. An IQ4 back will work on a purely mechanical view or technical camera. Where in the world are they hiding the brains that make an Alpa, Arca, or Cambo view or tech camera such a great conversationalist with an IQ4? What features does an IQ4 have, which an IQ3 lacks, which render it unusable on an H6x? I haven't seen any statement that IQ4 backs won't work on a tech camera because they would have to "limit the features of its backs so they can be used".
This sounds more like the kind of answer someone would give when they don't want to give you an honest explanation. An honest answer would have been, In order to deliver the optimum combination of image quality, features, and user experience, a camera maker needs to have control of the entire system. This is something that Hasselblad determined some years ago and which Phase One has come to realize as well (perhaps not by choice). In other words, when Hasselblad or Phase One or any other manufacturer has control over the design and integration of lenses, cameras, accessories, sensor system, and software an optimized system can be offered.
Of course, there could always be some financial considerations involved. Phase one now bears the full costs of keeping a camera factory operating in Japan to produce the XF and associated lenses. If a significant portion of IQ4 sales were for one or more cameras they don't manufacture, keeping what was Mamiya running might become more burdensome finacially due to the potential reduction in volume.
A Hasselblad H6 body seems to be plenty "smart" enough to run an H6D-400c MS with a full-frame 100 mp sensor in single-shot, 4-shot (full color resolution), or 6-shot (400 mp extended resolution) in addition to capturing 4k full sensor width RAW video. If you're using the HTS 1.5 adapter, it will display the precise amount of tilt, shift, and rotation on the camera body grip and transmit that data along with the lens focal length, aperture, and focus distance into the image file for automatic correction. It will automatically apply focus calibration information from the back combined with focal length, aperture, and distance data from the lens, and accelerometer data from the body to optimize focus calculations to account for sensor plane tolerances, aperture dependent focus shift (precisely calculated for distance and focal length), and degree of camera tilt or swing based on an enormous amount of stored lens data. Rather than go on, I'll just say that it seems to be reasonably smart and a pretty good communicator.
I'll end here. There is enough misinformation in your post that I think I'll take it in smaller bites.
