no it's not. And yes you SHOULD build this even as an adc and no it wont hurt your DAMAGE because you will actually be alive to deal it. Alot of damage is useless if you can't deal it.
It actually hurts your dmg because you bought tankiness intstead of dmg, which leads to you dealing less dmg than the enemy (except you play a champ relying on base dmg)
When Rengar is 29 and 0 and the adc still wants to leave tower. https://i.gyazo.com/255b01beda12719916fd5174ca13ad8f.jpg