When trained steps are not self explanatory, step notes are very helpful! They would be even more helpful if you could tell they exist or not :)
A short use case (based on a mostly true story)
QA#2 attempts to edit a test that QA#1 wrote.
QA#2 is confused about a step in QA#1's test.
But QA#1 is tied up in a very important meeting with his boss trying to convince her that she should up the company's monthly mabl run count!
QA#1 left wonderfully helpful comments on several confusing test steps, but QA#2 had no idea they were there :(
So to attempt to fix the problem, QA#2 spends 3 hours chatting with mabl tech support trying to figure out how SVG element query selectors and path definitions work because he had no way of knowing that QA#1 already annotated a workaround in a step note comment.
But QA#2 eventually figured it out, the company continued to use mabl, and they all lived happily ever after!