No, it does not "Shout". It is for the easier-to-read big print for all the old fogies on the forum.
I have old eyes, too, yet I disagree. All caps makes reading slower and is discourteous to the readers.
There are two very easy ways to increase to size of text on your computer: Hold the 'Crtl' key down and press the '+' key until you like the size, or hold the 'Crtl' key down and roll the wheel on your mouse forward.
On a phone or tablet, you should be able to increase the size of text by placing your thumb and pointer finger on the screen together, then sliding the thumb and finger in opposite directions.
All of these techniques can be undone by obvious reversals.