All ad champs get 5 damage buff on 7.20, why left darius over?

Because these buffs are compensation for the removal of AD runes. Champs now get higher base AD instead, but this leaves champs with primarily bonus AD ratios with less damage than before. Garen has only total AD ratios and Darius has total AD ratios on Q and W so no pre-emptive buffs for either of them.

didnt see one for garen yet either.

i guess theyll still get around to it, or its not documented yet.

Dafuq. I'd rather see Darius gutted to hell. At least Rito may be will notice that something has to be done about him