An alternate viewpoint to that, (I just toss it out) is that the process bases it's power multiplier on stock hp. Which, (theoretically at least) is the result of a myriad of items, some of those being the stock sensor set.

For example, Jeffs car, a Triumph TR8 from just after WWII, came with a pretty crude ECU, that lacked cool modern sensors, like crank wheels, etc etc.

Now, he can replace that ECU with one of his choosing, but the lack of certain sensors means he must look carefully at which one he chooses to ensure compatibility with the sensors he has/is allowed. This has, in effect, a limiting factor on hp. And that's actually good, because otherwise, his car, would over achieve and the Process prediction would be exceeded.

Now, those on the ITAC will hopefully tell you I'm not the 'lazy guy" on the committee, But we prefer to let the category run on as standardized set of allowances as possible, with the least amount of exceptions. Allowing free reign of sensors means that we could need to go back, and cull out all the cars like Jeff's, and apply a different power mulitipliers to better predict the final result. That's fraught with issues, and gets to a level of granularity I'm not confident in. Plus, it's a ton of work, and will lead to endless debate and second guessing. I'd rather not go there.