I didn't care about tabs vs spaces until I was handed a project to work on accessibility for a particular webapp, and that included firing up a screen reader.

That got me to learning about all the ways that markup can (and should) be used to convey _both_ the content _and_ the structure of the information on the screen, for the benefit of vision-impaired readers.

That in turn led to the epiphany that the tab character _is_ markup for indentation, and in the world of programming, where indentation is so significant for understanding (especially in whitespace-sensitive languages like Python), I wondered why we were making things harder for vision-impaired users by focusing so much on _visual_ consistency (which can still be achieved by syncing editor "how do I render tabs" settings)