Uppercase letters are used to emphasize a point. Maybe even try to shake'm up a bit. Psychologically it does. It's hard to tell, everything is in Caps. I need to make my messages in uppercase letters because the message has to shrink in order to get into my phone line and then show up big at the other end.
Caps are easier to read.
There maybe other good reasons why capital letters should not be used on a continual basis, but I think you get my point. Over time, It has become generally accepted that capital letters are used primarially, to emphasize a strong point and therefore should be used sparingly. This help page is especially designed to assist the users of Network Associates , an ISP for the greater Parkersburg W.Va. area.