The linked recipe is a great example. The 1/2 teaspoon in step 1 is never modified regardless of the scale of the recipe.
Also scale should go below 1 (like .5).
growing up, we had the old red/white gingham Betty Crocker cookbook where the scaled measurements were written in the book. the instructions never had any of the measurements in them. based on that, it just feels natural to the point of adding the scaling into the instructions seems overly complicated. just took a look at couple of other recipe examples, and they all leave out the measurements in the instructions.
1. I'll often use the ingredients list (and quantities there) before cooking to ensure that I have everything I need ahead of time. Depending on what ingredient it is, I might not mise en place it. In those cases, a step that says "add ingredient" would require me to go reference the list in the beginning, losing a bit of context.
2. It's not often, but I've followed a few recipes that require a particular ingredient in 2 different steps in different amounts.
Example: https://imgur.com/7qXRNTH