Some enemies have low to 0 physical armour, some have low to 0 magical armour. Focusing on only 1 is kinda dumb when you can break 1 for free. This idea completely nullifies that and makes everyone an armoured tank unless they lack both. What's more, different armour types block different cc affects, so only relying on one damage type can really hamper your options.

gambling on some rng cc affect is not a deep strategic decision. It's just a sign of gambling addiction.