You misinterpreted the quote...
They are saying that the 512GB drive can handle up to 72TB of write cycles. That is if you were to write 40GB a day on to the 512MB drive, you can reasonably expect the drive to last 5 years before you have a drive failure.
Yes, you're point is valid. However the point that the author is making and what Micron is saying is that these drives will last just as long as regular hard drives will last based on a realistic 40GB of writes per day.
The use case is within a disk array for database work. That is to say that most companies aren't writing 40GB of data per 512GB drive.
The point I'm trying to make is that if you put the use case of the drive and the statement in context, they are trying to say that you can use these drives in a commercial grade application.
A 2.5" 512GB SSD is probably a bit less costly that a PCIe card with 512GB of SLC. (Yeah SLC and MLC isn't an apples to apples comparison, but the idea of 512GB of Solid State Storage is the point. PCIe is very expensive.) For many applications where you want SSD, you don't need the performance of PCIe cards. So Micro does offer a better value.