Currently, we are allowed to have 38 attachments total, this includes HUDs and mesh/prim objects.
To some degree, we can link objects together, especially rigged objects, to help manage it.
However, sometimes we're stuck using objects that are no mod, meaning we cannot link them together to better manage our attachment points.
For example: Lelutka heads often come with several items that we wear, such as the head, teeth, beard, ears, the lel hud or point hud for animations. These can wind up taking away a chunk of items.
Now consider that some of us may also be using some gachas, and some clothing creators just still choose to no mod for whatever reason. We wind up with a large amount of objects we're wearing that can't be linked or managed.
By making it a 3:1 ratio you're throwing people a bone without encouraging people to make or intentionally seek out more no-copy things, but allows us to suffer a little less with the incidental no copy objects we already have.