For me, it's about not stressing about what's 'paleo' and just trying to eat a nutrient-rich, mostly whole foods diet that makes me feel and look my absolute best. It approximates the diet that my ancestors probably ate before agriculture, which makes intuitive sense to me, but I'm not at all hesitant to eat non-paleo foods in moderation as long as I continue to feel healthy and not see any reoccurance of my many pre-diet-change health issues.
I honestly don't give a shit about being 'compliant' to arbitrary rules about my diet, and I don't feel a second of guilt for eating things that aren't paleo. To me, that's unhealthy thinking - although I suppose it's very different for people who are doing this for weight loss and need to be strict to get results.
I've never had a problem with binging on junk foods, and while I definitely had strong cravings for wheat when first giving it up, I am now not at all tempted to eat foods that make me feel poorly. If I didn't clearly have gluten intolerance I would DEFINITELY make bread part of my '20%'- but as it is, not worth it at all.
I eat starchy tubers which many people don't consider 'paleo' - but I do. I also eat lots of dairy (well, mostly dairy fat, and some cheese) and white rice. With more moderation and more rarely, I also drink beer and liquor, and eat corn tortillas, sugar in ice cream and chocolate, hummus, and other beans.