Runes are generally EARLY game boosts, NOT full build boosts. And sorry, but if an ADC with a full build WITHOUT 20% CDR runes does no damage, then you simply suck balls at playing ADC. Simple. BT/BotrK, IE, LW, Shiv/PD is loads of damage on any conventional ADC. Your 20% runes aren't magically making it better. Especially not since your build would take 20 minutes longer to build simply because you have ZERO early game power. Sure you might get a magical double crit once every 400 tries that wins you a trade, in pretyt much any other scenario you won't and their adc simply laughs at you.
And you build IE, because 1. It gives you tons of AD, and 2. Loads of crit power. Why? Because again, a conventional build WITHOUT CRIT runes gives you enough crit. Simple. You having 20% crit early game does not mean you WILL crit 1 time every 5 attacks.
But hey, apparently you're a pro since you played ADC a few times. Have fun where it works. Come back when people have no problem whatsoever dealing with you.