What's in a line? That which we call a line
By any other view might look less sweet.

For example, if you're reading this post on a phone or some other small screen, then you might not see the line break that falls between "call a line" and "By any other," and you might see other line breaks that aren't supposed to be there. That's a bigger mess when the poem gets longer than two lines, as in electronic books of poetry. Publishers Weekly has an excellent article by Craig Morgan Teicher about the difficulty of showing poetic lines in electronic books.