ALL CAPS IS EFFECTIVE FOR TECHNICAL WRITING WHERE THERE IS NO VOCAL INFLECTION. EGGSHELL WHITE WITH 3" NAVY BLUE TRIM ALL SIDES. MAXIMUM FEED RATE NOT TO EXCEED 12FPM. I READ ALL CAPS TO BE MONOTONE, STILTED, AND NOT UNLIKE ROBOTS IN OLD MOVIES. Mixed case is like listening to C-3PO in Star Wars. C-3PO was popular as a robot because his speaking style included vocal inflection. I think C-3PO would not have been popular if he spoke in monotone.
No, I do not find it strange that all caps is SHOUTING. It is a commonly accepted method to convey meaning beyond the written text.
Selective capitalization adds a vocal inflection not possible with text. I recently saw a proposal for an ironic font. That should be good. There is, of course, no way to hear how I inflected 'that' in the previous sentence. Did I say it with ironic inflection or in a supportive voice? ThAAt should be good vs That should be good. Selective capitalization allows better expression.