Why I'd Rather not.

All I could think of when I came to this...

The problem with typewriters was that they used monospaced type—that is, every character occupied an equal amount of horizontal space. This bucked a long tradition of proportional typesetting, in which skinny characters (like I or 1) were given less space than fat ones (like W or M). Monospaced type gives you text that looks "loose" and uneven; there's a lot of white space between characters and words, so it's more difficult to spot the spaces between sentences immediately. Hence the adoption of the two-space rule—on a typewriter, an extra space after a sentence makes text easier to read. Here's the thing, though: Monospaced fonts went out in the 1970s. First electric typewriters and then computers began to offer people ways to create text using proportional fonts. Today nearly every font on your PC is proportional.

 was Dan Rather.