This is pure speculation:
Your enemy wears the shiny gold armor of doom. It has 50 physical armor and 100 magic armor, but you do not know this. You use a skill and see 80 damage, but you do not know if you damaged the armor or the enemy HP. If your skill did physical damage, you broke the armor and the enemy may be hit by physical status effects (some enemies may be immune because of what they are, like skelletons do not bleed). If your skill did magic damage the enemy still has 20 magical armor and any status effect will fail.
If there is still a health bar at enemies you could see if the armor is still there (unless the bar shows the sum of armor+health).
Do you think this speculation is plausible?

Prof. Dr. Dr. Mad S. Tist

World leading expert of artificial stupidity.
Because there are too many people who work on artificial intelligence already