I agree with you that MSFT using their own file format is not abusive, but it's also true that Word has traditionally (say, last 20 years) had a MUCH MUCH large

I agree with you that MSFT using their own file format is not abusive, but it's also true that Word has traditionally (say, last 20 years) had a MUCH MUCH larger market share than anything that came before. Its closest real competitor was WordPerfect, but by the time the world shifted to Windows versions of thing (ie, not DOS versions), WP's goose was cooked and the only real player in offices was Word. It's not that way now because of inroads made by online tools / web-native things that make traditional document production less important than it used to be, but they're still the 400 pound gorilla. They're just not really a monopolistic gorilla.