Not really that hard to do
When the performance of a node with 10 SSDs is basically no greater than the performance of a single SSD, it will obviously have something like 10X the lifetime of a single SSD, so even if it was in use constantly it is likely that the lifetime will be longer than anyone will leave the box deployed for. Or as Yet Another Anonymous coward pointed out by the time you discover that you can wear it out the cost of replacing the array will be a lot less than it originally cost to buy it.
So it's not that they did anything special to be able to make this claim, other than being really slow.
