Why do editors (such as MS Office apps) have so much redundancy?

Trivia

This is my only question on Stack Exchange ever to get more than 10 votes.

This is also the only question I´ve asked on Stack Exchange while drunk as f***.

Lesson learned I guess.

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I'm thinking of making an editor and how it should differ against other editors. One of those points are promoting the work area over GUI buttons and information fields. Tool bars, menu bars, scroll bars; I want it all to go away and be replaced by something not taking any space on display. That "something" is irrelevant for my question.

As an example there is MS Word. More or less every command can be found in menu bars, tool bars, some more bars in the bottom with "good to have" stuff, context menus in the workspace and as dialogs. Many actions also have keyboard shortcuts. Everything everywere. I mean just look at the new, open, save buttons. They are literaly neighbours to the menu bar variant! (I know this changed a long time ago for MS Word but I see the same pattern for other editors. I also happen work in a secret bunker still using Office from 2003 to 2016)

Because I plan on removing most of it I must first ask: Why all this redundancy? What purpose does it serve? Is it all about legacy and familiarity with previous systems? Targeting a broad and diverse user base? Am I missing an important point in not having "everything everywere"?

A more modern UI worth mentioning with this issue is Visual Studio 2015, although actual redundancy is percieved lower and my biggest problem being "stuff, stuff everywere".

As contrast, I find UMLet being a breeze to work with from UI perspective. I do realize how unfair it is comparing tools performing different tasks, but I hope you get the idea anyway.