Compatibility
I didn't use word perfect until 1996/7, and the version then was actually quite good for professional users, once you got used to it.
But the worst problem was document compatibility, exchanging documents between organisations with Microsoft, Lotus or IBM Displaywrite was a problem, but mostly on the Microsoft side. Word documents rearely loaded into the compeating products without problems, though the reverse was not the case. Word had no problem with other products.
I also noticed that, for some reason DDE calls to Word worked better from non-Microsoft products, and that DDE calls from within never quite worked as well.
Government bodies by this time were looking at choosing new packages to eliminate these issues, and tended to let the user community decide, which was usually for Word and Outlook, because they had that at home. You could always get a good package deal on a new PC with Office.
Fast forward a few years and the other vendors had more or less given-up, but Open Office was around, and again the problem was that the published MS document Standard was not the same as the output from Word. Although I think that was and still is down to cock-up not conspiracy.
All in all, Office would have won anyway, because it's a better marketed product, but we now have a situation where there is no real choice, once you take the Microsoft pill, you take it for life.
Lotus, and Novell failed to respond to Microsoft's strategy in an effective way, and thus lost. Undoubtedly some of their behaviour was anti-competative, and they should be held to account, but 17 years down the road, what real punishment can you inflict, that makes sense.
Ultimately, we put Microsoft where it is now we have to live with it.