Article states that win 3.0 used 32-bit flat addressing mode, but when win 95 launched ms said win 3.0 didn’t (in 386 mode).
However, Win32s was introduced in 3.11 which a subset of the Windows 32-bit API from NT.
3.11 also introduced 32-bit disk access and 32-bit drivers.
Microsoft did 32-bit in steps -- it was confusing already back then.
IIRC a lot of it wasn't turned on by default due to hardware/driver compatability concerns, and there were articles all over the place about how to turn it on for extra performance. Essentially they used optimising tech-heads the world over as a giant beta-test group for parts of Win95's IO subsystem.
They gave us a win3.1 computer and Spyglass Mosaic which required the Win32s susbsystem.
http://www.win3x.org/win3board/viewtopic.php?t=4971&view=min
The full time guys all had a Sun on their desk next to their PC. We also had to run an IBM 3270 terminal emulator and X server to connect to the Suns. It was all so unstable. I rememember a bunch of "Win32s error" popups.
The other intern and I found a room full of decommissioned 486 machines, installed Linux and didn't tell anyone for a month. Everything worked great and then we started an assembly line of installing Linux on those old machines for all the older coworkers to take home.