Actually, I didn't make that statement. I made a statement saying that the withdraw can be opioid-like, and another saying that nicotine is one of the most addictive substances in existence. Let me clarify both, then.
The addictive level of a substance is not measured about how easy it is to quit, but about how easy it is to get addicted. I have no doubts quitting heroin is much harder.
Also, when I talk about withdraw being opioid-like, I'm speaking about it being possible (not mandatory or even the rule) to present with symptoms associated with opioid withdraw. Specifically crams and throwing up. However, while those symptoms are frequent and stronger with opioid, they still can happen, even if more rarely and in a milder form, for nicotine.
Another important thing to notice, in a more general way, is that "easier" is a very relative term. It is easier to survive being shot in the chest than being shot in the head. Doesn't mean you should feel safe in either case, or that either case is EASY.