I pasted the results of typing man rsync into my macbook’s terminal. I looked up the —delete parameter and pasted the entry. Not sure why your entry was more useful - perhaps a version issue (which is at the root of the painful time I have spent trying to learn how to do something trivial).
Later in the man page, it gives examples and totally fails to explain those examples. And yes, for someone who is going to be doing this frequently and professionally. They should understand this deeply and spending the hours required to be fluent in a command with a kitchen sink full of parameters. I, on the other hand, will be executing these commands maybe a few times in a year.
The more I think about it, the more I think the solution here is to use LLM‘s to write better documentation with lenses for different types of users with different needs.