What has happened with mobile platforms has proven that the fact that we ended up with PC platforms that all us the freedom to largely do whatever we want with them was more an outlier than the norm.

Apple and Google have gone out of their way at every step with their new platforms over the last 20 years to make sure that process does not repeat itself. Even the stuff that seems more open like Android technically supporting arbitrary app installs from anywhere and the Linux container in ChromeOS still allows the platform holder to step in and stop you from doing something with those tools should they desire using mechanisms that the OS depends on to be useful.