I agree that the "bridge" should be built to the expected capacity + additional due to uncertainty, but that's a slippery slope and one that this article is try

I agree that the "bridge" should be built to the expected capacity + additional due to uncertainty, but that's a slippery slope and one that this article is trying to address. It's a judgement call on what amount of work is appropriate for what amount of capacity, as adding on more capacity due to uncertainty might delay the product or solution from launching. It may be more appropriate to properly separate concerns and build a flexible architecture that can be upgraded over time to meet needs as they come, or left as-is if those needs never manifest.