[illumin8]

With any system of sufficient scale, you're bound to hit artificial (software design inflicted) limits to maximum scale or performance.

The reason why a good software company tests extreme limits (1 million containers) that most customers will never see is to ensure customers that they will not reach a scale limitation.

From my experience running large private cloud infrastructure (>14,000 virtual servers at once), you will always hit some crazy limit that the vendor never anticipated. "14,000 VMs? We've only tested with 10,000" (not a real example, but an idea of what type of problem you'll run into)

Proving 1 million containers in 5 minutes is just designed to assure regular customers that they're fine. I doubt anyone really needs that many containers for any current workload...