Many are some aren't. With the bundles especially the ones that are offering bigger discounts you're looking at something that is not moving well in inventory that is being paired with a desirable and compatible part. So you'll see something kind of odd like a high end CPU (R9 or I9 cpu) being paired with a mid tier micro-atx motherboard , they might put in a middling amount of ram as well, then it will be priced at a point where you're getting either the motherboard or the ram at about 70% off.
That said in a lot of cases it's weird detail stuff and if you sift through them you can lots of times find something that's a very good value for you and your use case.