For every article you find about why coffee is bad, you can find one about why it is good. And just because Mark says it's primal, doesn't mean it's good for you. He also says he puts a pinch of sugar in it, yes SUGAR! But he also says he only drinks a cup of it a day. I follow Mark because he is practical. He considers the pros/cons, and tries to eat as close to perfect as possible but is also realistic about our needs in this day and age and makes the necessary compromises. Maybe it's not truly primal from a hunter gatherer perspective, but it's not going to kill you, doesn't have any negative health impacts for most people, and life is meant to be lived and enjoyed so why not?
It's really going to depend on your health, situation, consumption, ect. to determine whether coffee is going to have a negative impact on you or not. I have given up coffee before for months and was just fine, I started drinking it again because I really like it. I love the taste and I feel a noticeable improvement in my mood, and am just much happier when I have a cup of coffee. But I drink it in moderation and don't rely on it to get me through the day. If you have a cup or two a day and don't rely on, then I don't see the harm in that. If you're drinking half a pot just to get through the day, you may want to consider cutting it out for a while then phasing it back in at much lower doses. Just like many foods, coffee can be an acceptable and healthy addition to your diet, but it can be abused like a drug and have similar negative effects so just be smart about it and don't sweat that morning cup.