I think it's akin to a superstition. Or perhaps it's displaced anxiety. Whatever it is, it can be a new writer's nightmare: Striving for perfection.
One writer I knew agonized over format. The pages had to have exactly twenty-seven lines each, double-spaced, no more and no less. Yet there could be no "widow" lines (single lines of new paragraphs at the bottoms of pages) or "orphan" lines (last lines of paragraphs stranded by themselves at the top of a page).
Endless rewriting and tweaking to get just the right look.
And the headers - good Lord, the headers! Should the name be in the upper left corner, the title in the upper center, the page numbers in the upper right? Was boldfaced OK? Should the title be italicized? How many spaces after a comma? After a period? After a semicolon?
That way, as soneone observed, madness lies.
Face it: You will never achieve perfection. Your responsibility begins and ends with producing a professional-looking manuscript, formatted as close to the publisher's guidelines as you can manage. You're going to mys a typo here or there. Your spacing will be off somewhere.
Doesn't matter. You're not getting a grade. Neatness doesn't count, beyond the standard double-spaced text, twelve-point type, paragraphs indented, no extra blank lines between paragraphs, justified left margin, ragged right, one side of the paper only, black ink, and a standard font like Times or Bookman or some such.
Because the neatest formatting in the world won't save a crappy story. A great story will win the writer forgiveness for grievous errors in formatting.
So tell the story, and do it as well as you can. Don't waste your time striving for an unreachable star. That only counts in musicals.