Clear menus that aren't hidden away are great, but a significant problem with horizontal 'sausage' menus is that it isn't obvious that you can scroll, especially on Apple devices that hide scrollbars. The article mentions this as a bit of an after-thought ("Without proper fade / cut off visual cues, users may not understand they can scroll") but it's the key reason why you should avoid them.

To demonstrate, I've forked the example and set the main element to 625px wide instead of 600px - https://codepen.io/onion2k/pen/mdpVWmr