Because you got me curious enough to look this up: It apparently originates from typewriters, when holding shift was quite physically taxing (since it literall

Because you got me curious enough to look this up: It apparently originates from typewriters, when holding shift was quite physically taxing (since it literally shifted all the typeheads over to put alternate characters over the ribbon); so caps lock saved a lot of finger strain when typing acronyms or writing symbol-heavy text.