[{quoted}](name=Playing Sona,realm=NA,application-id=3ErqAdtq,discussion-id=Ab0JaJk2,comment-id=000100000002,timestamp=2016-09-15T17:22:33.572+0000)
That's what those items are for.
Oh look!
You lose 15% base attack speed because of
.
You lose 40% base move speed because of
.
You get healed for 10% of your base health because of
.
exists.
yet there is no combination of slow items that would allow someone to automtically slow an opponent by 90%
because it would be broken.
im not questioning that there are individual items that can reduce or penetrate armor. im critisizing that they can be stacked to the point where 200 armor turn into 60 or less.
i can make the same argument for 
there is one item that reduces attack speed slighly. not 5 items, runes and masteries that can be stacked to set someones attack speed to 10%
its the extreme case i want riot to get rid of, not armor penetration or reduction as whole.