When I was thinking about the "additive" vs "subtractive" approach, I specifically thought about cell phones, or more specifically, the iPhone. Whenever Apple introduces a new iPhone, they don't attempt to restrict a key feature from the phone - rather they go all out and try to cram as much as they can into each successive iteration of the phone. Same goes with Apple Watch and any other Apple product for that matter.
Same is true with Nikon and Sony. Sony for sure is using an additive approach, cramming as much tech as they can into their cameras - mostly due to the fact that they were the underdog and had to prove themselves, but even now they continue to put as many features as they can. With Nikon I think its the same thing to be honest - with the D800 they arguably took a huge risk putting a huge MP sensor into a camera like that while putting a lower MP sensor into their flagship D4. But they still went ahead with it and were able to successfully separate the two lines. While the Nikon Z certainly is missing features, I feel it is more due to Nikon's lack of R&D money vs Sony and Canon and them having to focus on specific features versus others.
With Canon, I just feel that there are outright obvious examples where features have been subtracted for no reason. Not having C-log in the 1DX Mark II is the perfect example. How do you justify putting C-log into the 5D Mark IV and now the EOS R - both which have crop and rolling shutter, but you don't put it in the 1DX Mark II which has less crop and less of a rolling shutter problem? Just makes no sense to me.