Microsoft game files are strange

Hello

So i bought skyrim on pc for the windows store and you cant install a script extender which adds a much more diverse range to mod your experience.I found an article from pcgames which says:^^ By default games acquired through the Windows Store, including those on Game Pass for PC, install to unchangeable read-only directories, making them impossible to mod. However, some games have a toggle to alter this, meaning the Game Pass versions of FTL, State of Decay 2, and a handful of others actually can be modded^^

So why are we so limited if we own this game/license and cant do what we want?