Why Indent Code?

Indentation obviously makes code easier to read and parse (by humans). It is obviously very important.

But it leads to many annoying issues, say with git tracking line changes (if I un-indent a code block it is all marked as changed even though the logic behind it hasn't, so a reviewer shouldn't waste time looking over the changes). Also having to configure your editor to indent correctly and the creation of many indentation rules. It makes reaching the "80 character limit" come much faster depending on how you indent code and pushes code off over your screen so you have to use line wrap or scroll sideways.

I was thinking, why not instead of indenting the code we could not indent the code and leave it to the editor to handle formatting it visually.

Now any editor will be able to parse this and display it how I would like. Say I prefer 2 space indentation it can do that instead of 8 which others prefer. Maybe I don't like indenting the code and instead would like the first "indentation" level to be underscored green, the second blue and the third red. Well it would be up to me.

Is this a horrible idea? I think it would solve a few problems and doesn't cause many problems.