i disagree with that since there is less mr in general because their are less penetration options and 5 armor being removed would be a massive buff to lethality users since that means that ad champs have a weaker response to them stacking lethality before grabbing a tank item or ga late in their build
edit: some math if ignoring lethality runes
masteries will give you 6 lethality+15 from edge of night+15 from yuommus gives 36 lethality and 22.4 armor pen at level 1 which would negate the armor from tabi's almost completely, but this would be it doing its job since now you have your base armor left. but at this point in the game you would probably be around level 9-11 and at level 11 you would be ignoring 30.4 armor, overshooting the new tabi's and cutting slightly into the base armor of the target, considering how powerful the movement speed and the spell shield from these two items are and the 120 ad you get from it being able to cut even slightly into an adc's base armor instead of only ignoring bonus armor is a large buff to the likes of jayce and jhin since there poke now hits harder and over time it will add up alot