If the primary purpose of Zorin is to appeal to windows users & not existing linux users, then the main thing holding back Zorin is the use of the gnome GUI.
Zorin makes gnome look like windows but doesn't have the features and settings you'd expect from the windows interface, there is only one linux GUI that comes close which is KDE.
KDE has the settings, features and integration windows users come to expect, no other linux GUI comes close and I've tried all of them.
Valve are also funding KDE's main developers, they understand windows users are not going to migrate to an environment were they feel out of their depth or completely alien to the way windows works.
Which is why the Steam Deck features KDE as its desktop and not gnome. KDE is only going to get more polish and feature parity with windows thanks to Valves very deep pockets and an actual mass market product using it.
Sure there is Kubuntu but Zorin can do a better job and Linux Mint Cinnamon is too rough around the edges, it ships with UI flaws no commercial product ever would.