I definitely agree its only a "make you feel better" thing. The 1st part apps are using shared core resources that can't be removed. In iOS 10 it would just hide it from the user. In iOS 12 and later the many application files can be removed but the its not going to remove its shared libraries. Apps that are used as a central repository for their framework can't be removed at all (Home, Health, etc), doing so would break 3rd party applications that use them.
Apps like Pages, Numbers, iMovie, etc (not sure if those are preinstalled or not) can be removed for substantial storage savings.
If I go through the process of deleting and reinstalling a 1st party and while running Console and Xcode (stocks.app)....
Application running, its shows /var folder since the data contained within will vary wildly based on usage.
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Delete Application.
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Console goes on for miles so I just grabbed a couple more obvious portions.
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Application no longer running of course...
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Try to use a universal link from safari (ex. stocks://?symbol=AAPL) to verify the stock.app isn't accessible...
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Going to the app store and redownloading the stock app finds no data cached locally...
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Network Activity Log in Xcode sees the app download.
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Console of the downloaded installation.
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Since Xcode crashes every time I try to use Filesystem Activity instrument I wasn't able to tell if it let me see the rmdir/mkdir process and all that.
Its about as good as they can do with so app dependancies and its better than just making the icon disappear.