Idea to make asmdef assemblies actually usable

There's probably no way that what I'll describe here wasn't mentioned before but here it goes:

https://docs.unity3d.com/Manual/ScriptCompilationAssemblyDefinitionFiles.html

I was really confused by this image as somehow I thought "Precompiled Assemblies" are not only Plugins but also all scripts in Plugins/ folder. It turns out that those are "Predefined Assemblies".

This approach doesn't make sense to me. How "firstpass" requires access to asmdef assemblies? Wouldn't it be possible to move Assembly-CSharp-firstpass.dll (and the editor version) in that chain to Precompiled Assemblies?

This would fix issues with Editor folders and asset-store-plugins that use many of them as they could be just dropped to Plugins folder, compiled to Assembly-CSharp-Editor-firstpass, done.

The only takeaway is that firstpass can't see asmdef assemblies but noone does it anyway, right?