Re: Marketing
The TLDR response is that OS/2 had a number of decent, technically able applications but with the best will in the world the win32 market was orders of magnitude larger, win9x was 'good enough' for many users and NT usable for others. Games started to move to Windows and by 1997 that battle had been won.
You're absolutely correct that people use applications not operating systems. The problem as I see it, at least at the consumer end is that OS/2 had its own culture of entitlement. The users expected programs with equivalent functionality for a Windows application, technically superior to a Windows application, adapted to OS/2, for a similar price to a Windows application. That is simply not going to fly for a minority platform - they don't have the economies of scale.
The way to win with a minority OS is to pay a little more for less but higher quality functionality than the market leader. That's a big ask for a lot of people who still have difficulty understanding that the best way to get a printer that works is to pay more, not buy a thirty quid pile of crap with extortionate ink prices from the supermarket.
In the crucial period between 93-96 OS/2 had :
Lotus AmiPro. It wasn't very good - had a lot of horrific bugs. By the time WordPro made its way to OS/2 it was using the win32 compatibility libraries, and the operating system wars had already been lost
Star Office. Not actually a sizable competitor at the time.
IBM Works (bundled with Warp 3). Actually reasonably good, if a little buggy.
Describe - technically brilliant word processor/low end DTP package. Lovely printer output. Sadly it had no word counter (you had to program one in REXX. It was a frequent complaint, but was never added), and for long documents it was frankly a complete chore to use.
Mesa/2 - stunning spreadsheet. Far better than Excel for a number of purposes at the time. I was still using it in the 00s because Excel was limited to something like 32K rows, and Mesa had no problem with manipulating a million plus.
various other older or minority office apps
There were a number of VB like development tools for OS/2
OS/2 did have a reasonable amount of free software, but sadly a notable proportion of the userbase had a Windows mentality where they thought software should be provided to them without effort.
It was far too easy to run win16 applications under OS/2 without supporting OS/2. My shame is that whilst I spent a considerable amount of money on OS/2 applications, when I wrote my university dissertation, I used : AmiPro under WinOS/2. Describe was simply too much of a pain for long documents, and additionally AmiPro was available on university computers whereas OS/2 wasn't installed anywhere.