Windows 3.0 wasn't object oriented. It was written in assembly and C, so there weren't any classes to build a class map from. I know, it's hard to believe these days, but that's why the Tools team and in fact almost everyone else implemented their own GUI controls.
The same was also true of MacOS. The Xerox Parc people did demo Smalltalk to Steve Jobs, but he was too bedazzled by their GUI work to notice. It was only later he realised how important object oriented software was, and ran with it at NeXT.
In fact this difference is even visible today. NeXT built their OS GUI layer up from low level object oriented frameworks and these are what you use to build applications. The entire structure of the OS is oriented around enabling the creation of applications. The modern Mac of course inherits this approach. On Windows the OS is mainly services applications can use. There is of course a suite of GUI controls and components but they're very basic. Microsoft's developer tools are a different silo, in fact several silos. That's why they are forever coming up with new fancy GUI frameworks sitting alongside the native controls like MFC, .NET Forms, WPF, etc. Now they've finally given up and adopted Electron.
But reading this you can easily understand how MS didn't understand what was going on. I've never been a fan of MS culture or MS products, and this insider view hasn't changed that.
While I realise it's a first person account, it doesn't answer obvious questions - like how how Windows got to version 3 without a class map, or some proto-equivalent.
Or if it did have one, why the Tools team thought they could write development tools for Windows before 3.0 without abstracting it, or referencing it, or something that wasn't in direct competition with it.
Or why anyone would think that building generic yet somehow also OS-aware tools in a moving target language like C++, that were equally suitable for DOS, OS/2, Windows, and maybe UNIX too, was even feasible, never mind a good idea.
And so on. More questions than answers. I'm much less interested in the fact that Sinofsky bought some t-shirts or worked out that shipping matters than in the decisions - or sometimes the lack of them - made in the background.
Given all of that - perhaps it really wasn't a surprise that MS couldn't see what the Internet would become in 1994, even though a lot of other people could.