Carob Semantics Are Important
I applaud you for not using lazy language in this post to describe carob as "a chocolate substitute."
As you say, carob is "definitely not chocolate." While it LOOKS like chocolate and shares some physical characteristics such as color and texture, it's definitely NOTHING LIKE CHOCOLATE. It's a completely different product.
So, I would suggest that carob can be SUBSTITUTED FOR CHOCOLATE in some recipes or even as a stand-alone snack, that it is definitely NOT a "chocolate substitute."
That misstatement can make a very large difference in whether a person will like carob the first time they try it. If they're expecting a "chocolate substitute," they're going to be seriously disappointed.