Re: "by Dave Cutler, who Microsoft hired as the NT team leader."
However aren't most of the desktop Windows from a later, not NT code base?
No. Windows 1.x, 2.x, 3.x, 95, 98, and ME are the non-NT desktop Windows versions.
Windows NT 3.x, 4.x, 2000, XP, Vista, 7, 8 and 10 are all based on the NT kernel (with various pieces added/removed/rewritten over time.) 2000 was the last NT version which used the same name/number for server and desktop versions, but Server 2003 is based on the same major kernel as XP, 2008 is based on the Vista kernel, 2008R2 on 7, 2012 on 8, and 2016 is based on the 10 kernel.