What would be the benefit of having more than one word processor, compiler, database, operating system or photo manipulation system? I say competition and inn

What would be the benefit of having more than one word processor, compiler, database, operating system or photo manipulation system? I say competition and innovation as well as selection. For browsers security. How can I mmention security? Well, if Chromium has a serious bug, it impacts millions and millions. Having different engines should hopefully mean some are immune to that particular one so you cant win the grand prize with a hack for one engine.