It’s all about maintaining 3 points of contact when moving a limb. 2 feet and a hand or 2 feet and a hip/knee when using both hands. If your feet are on the top step then you don’t have a knee or hip to keep the 3rd point of contact. And stepping on the top cap means no where to lean onto if you lose your balance (this one is self explanatory).
The original article talks specifically about flooding rice farming. https://www.straitstimes.com/world/europe/your-bowl-of-rice-is-hurting-the-climate-too
Apparently, flooding the field kills weeds but allows the rice plant to survive. The plant matter decomposes and releases methane gas. The article’s main point is to bring awareness to a planting technique that doesn’t produce methane gas. It’s clickbait more than corps doing there “take individual responsibility” thing.