to me, this rly makes no sense considering that there are pretty much more champs that prioritize in magic damage rather than physical is it is quite rare to find a full ad team to stack all that armor with. i think some new mr items shuld b made.

All champs do physical damage.

Because autoattacks exist.

Health is like a secondary magic resistance because magic damagers tend to be more reliant on burst, and thus less powerful when their target doesn't die, where physical damage just keeps autoattacking.

Armor is in higher quantities than MR because DPS don't have a cooldown. AS lets them hit like twice in a second.

This is also the reason Casters get a higher % Pen value than DPS.

so i shuld b afraid of an ad annie?

Basicly, most AP relies on burst, with cheap plentiful magic resist the burst drops significantly. This is why there are very few options for anti-burst. Also AD is every attack, the only champion that you might be able to compare it to is Karthus (Spamable Q and DPS area with almost no cooldown) even then ratios limit AP champions significantly.

cuz ADs can atack all the time and APs no