It has nothing to do with protecting anything. People who would buy a cinema camera would not buy these cameras irrespective of whether 24p was included or not.The 90D can't do p24 either. It's the Canon cripple hammer at work. They're protecting their Cinema cameras. They're not going to let their ILC cameras shoot 4K footage that's competitive with their Cinema cameras or shoot p24. Market demands/expectations have basically dictated that Canon can't sell 4K with a crop anymore or just omit 4K so they're offering full frame 4K but crippling it in different ways. Prior models have omitted it, disabled dual pixel AF in 4K, had a substantial 4K crop, had horrible rolling shutter in 4K, or had other ways to keep a clear distinction in 4K footage quality and usability between the ILCs and their Cinema cameras.
Canon operates in a delusional fantasy land where you will either buy a Cinema camera from them if they don't offer good 4K and/or p24 in their P&S cameras or ILCs or just buy them anyway and just accept the limitations. In reality you will likely buy a camera from someone other than Canon instead if you want competent video.
All of the things you mention are actually hardware limitations which result from cost saving measures necessary to make an affordable consumer camera with the technology available to Canon, not "crippling". The hardware in Canon's cinema cameras is a lot more sophisticated than that included in consumer cameras, so of course there are going to be compromises. EOS-C cameras have specialized processors and sensors, both optimized for video, plus a lot of other dedicated hardware intended to facilitate video. Consumer stills cameras are far less capable in that respect. It is not just a case of flipping a switch, the cheaper cameras are literally missing a whole bunch of hardware required to implement those things.