Just like disabling JavaScript in the browser by default, or using LTSC versions of Windows --- it's propaganda to keep you on the path they want, and not the path you want, because there are powerful interests in the former direction.
If this was true Apple would have never released the lockdown mode feature. A good conspiracy theorist will drop a theory when there's clear proof they're not up to anything.
Much like LTSC and the ability to disable JS still remains, it's merely a concession they don't actually want you to use, and in the case of lockdown mode, serves as a feature to tick off their privacy-oriented marketing.
