I did not think DR wrote IBM PC-DOS. I thought PC-DOS, as packaged with IBM PCs, was written by Microsoft, who also sold it separately (with some embellishments) as MS-DOS. Even then MS marketing had created a perception that they were the Gold Standard and I remember at work some guys wingeing bitterly that their corporate PCs came with PC-DOS and not MS-DOS.
In those days many PCs were sold with no operating system and DR stepped into this market (after some shaky starts) with DR-DOS, the "third way". DR-DOS was probably superior to the other two but MS deliberately put spoiler code in Windows 3.1 to prevent it being installed on DR-DOS [Look up "AARD Code" in Wikipedia].
DR-DOS was bought by Novell and then Caldera. I have Caldera DOS 7.01 on three floppies on my desk right now and I used to use it at home. It was free to non-commercial users.
If Windows 98 was the first OS you saw crashing you cannot have used Windows v3. Windows 3.0 was the first OS I used and it was truly awful - it would crash about once per hour with the dreaded UAE (Unrecoverable application error). It could not withstand an application crashing, but I think it always blamed the application anyway,