Apple (not there unique in that) has a long history of Application abandonment, at least for their paid Apps, which is not very intuitive. I am too tired to list them all. You can start Macs platform I suppose... The first I remember was there Word Procecssors Macwrite, Macwrite Pro? Clarisworks, Appleworks, Bento. I am sure there is more.

When one chooses a a program one hopes it is elegant and useful. An important feature though is its longevity so that the files can be read in the future.

There used to be dedicated conversion programs were popular and most Applications could read and write to a number of formats.

MS Word has a pretty powerful feature called read and file that successfully imports at least body text.

While were on a word processor kick my most beloved word processor was only partially developed by Apple and was developed for many years by an outside company. WriteNow. One of the most elegant and fast word processors of its day. Writeen in machine language.