It's network effects / lock-in. There is a reason why people still use Microsoft Office and that is that surprising amount of industries have everything build around it. In my country anything law related is submitted in Microsoft Word. Academic texts? Microsoft Word. Communication with government? Microsoft Word.

The reason why Google Docs somewhat managed to break this was 1. free, 2. multiplayer/easy to share.

One law about requiring the state documents to be submitted in open formats, editable in libre software... and the lock instantly breaks.