User blog comment:QuantumFeint/The Skirmishing ADC Experiment/@comment-24795478-20150607085804/@comment-24795478-20150609005323

In reality, a tank dont have enough damage to put you down immediately in the current 4 seconds of being smitten, hence in that 4 seconds you dont really reduce that much damage. But as a tank, diving into enemy team mean the ADC/APC will attack him first, and their damage is not only bursting (APC), but also high enough that can a tank you within 4 seconds ( or even 6 second in previous patches), hello the newly buffed BotRK. Tank's job is to disrupt, not dealing damage. Even the top tier jungler and tank now ( maokai, sejuani, gragas ), still cant burst ADC down immediately.

Remember, ADC is the one dealing damage here, their only weakness is bursting, hence their counter are assassins and mage/ longrange mage. With just some lifesteal and arpen,ADC can take down tank easily ( maybe except shen and mundo ) because most tank dont have sustain.

TLDR: tank deal no damage to ADC, no need red smite. ADC deal load of damage to tank, they take red smite. IF there is assassins maybe red smite can be viable.