It removes a copy. There's still another one in the installation archive. If you have your system set to CompactOS mode, which you would presumably do if you were worried about space, I think it really would just be removing a link.This is not true in this case and is probably due to some interpretation of how packages are installed in Desktop editions of Windows.
In Desktop editions of Windows, many OS files (not all) are installed into the Windows "side-by-side" (aka %WINDIR%\WinSxS) grouped by component. What happens is that when the package containing the component(s) is "staged" (prepared for installation), the files are placed there. When the package transitions to an installed state, the files from the WinSxS are "projected" into the main part of the filesystem using hardlinks.
To further elucidate, Windows has two types of "optional features":
1. "Legacy" optional features
These are the ones that work like you describe. They are sometimes informally referred to as "OCs" (optional components). Packages declare a portion of their payload as a "selectable update" that is then exposed by the legacy "Turn Windows features on or off" control panel and by dism [0]. When one of these legacy features is enabled/disabled the selectable updates may cause registry state to change, but largely just "unproject" or "project" the hardlinks I mentioned earlier.
2. Features On Demand
These are the "modern" Windows Optional Features. They are sometimes informally referred to as "FODs" (features on demand). Unlike the legacy features, one or more packages are associated with a feature via what is called a "capability" identifier. When a package declares this identifier, Windows exposes this as a "Feature On Demand" via the "Manage optional features" settings panel and via dism [1].
Unlike "Legacy" optional features, when a FOD is installed or uninstalled, it actually installs or removes all of the packages for that feature and the associated payload, etc.
Where the confusion likely comes is from the fact that installs are still done the same way I described earlier. That is, files are placed in the WinSxS and then projected as hardlinks into the filesystem.
Definitely? Even though they completely removed mspaint.exe from some of the preview builds a while back?
Choices of which product features are supported are orthogonal to the Features On Demand platform technology. With that in mind, consider that unused features don't need to be downloaded, reduce OS footprint, reduce update downtime, and reduce bandwidth usage during updates all of which can benefit both the customer and the supplier.
I have no insight into product feature choices, but I would encourage you to take a broader view of platform technology choices and consider that they may be orthogonal.
[0] https://docs.microsoft.com/en-us/windows-hardware/manufactur...
[1] https://docs.microsoft.com/en-us/windows-hardware/manufactur...