To those completely oblivious to the main reason why Kindred was strong back then...
Let me tell you. When kindred was released, there was this lovely (/kappa) item called Devourer. When this item was transformed into Sated Devourer, it had the current passive of double on-hits that Rageblade currently has. They got a ton of damage from the passive as it amplified not only the damage from their passive but the damage from Blade of the Ruined Kind AND the on-hit damage from Sated Devourer. They nerfed it to 4 hits for ranged champs instead of 2 and this balanced Kindred but it didn't balance the melee abusers coughs Yi coughs. After they removed it and replaced it with Bloodrazor, it removed Kindred's need for BoTRK and they were in a good spot. Now Riot has hit them with nerf after nerf after nerf for no good reason. So there you have it. The reason why they were "strong" back then.