[LoL] Why do people not realize the difference between AP/AD, Magic/Physical, and other (easy) stat differences :/

Sick of people saying PHYSICAL spells are not working with Life Steal

Life steal only works with auto attacks and abilities that APPLY on hit effects is that hard to understand?

Spell vamp works with items/spells/abilities that are ACTIVATED (therefore no On Hit effect spells like Teemo)

and also only heals 33% of what it should for AoE spells (per target)