A bigger challenge I think would be new gen gaming consoles, this would be awesome. There does exist exploits for these I believe, but they are private and public ones get patched, then you can't play online or downgrade updates easily. Maybe it would be easier to stay on an older version and make your PlayStation think your on the latest version, maybe this is what those who have it do.
On windows, there are many problems you can run into by directly manipulating kernel structures, but that doesn't mean it cant be done safely, especially on things outside of something like win32k which is a mess. Hooking things won't get you in trouble, unless for example you're hooking integrity checked functions or data regions on Windows and get patchguarded. Which doesn't run everywhere on the windows kernel and can be maliciously disabled, not even ntoskrnl executable sections are fully protected by PG.
I have no problem with that by the way, but you are on your own lookout and should accept it as part of the deal. Similarly if I damage engine performance due to bad tuning it's my problem, not theirs.
I do think it's too broad of manufacturers (whether car or phone) to apply a blanket warranty denial in such cases. But in the phone case, no reason apple should accept bug reports on a jailbroken system if it can't be reproduced on a "stock" one.
Ad tracking should be so high up in the stack that for a change that far down to cause issues then far more significant issues should be occurring at all.
If your system has to be balanced juuuuuuust right to function it's a poorly engineered system.