The point of the bounty system:
Bounties are good for the author of the question when no good answers have been received.
Bounties are good when you find a question that has not received a good answer and it is already worded well to accurately describe what you, also, would like answered.
If an older question has been referenced as having the answer, it means it already has one or more answers that have been indicated as good, either by upvotes or being accepted. So that question, as asked, is already well answered. What would a bounty accomplish? Even if it produces more answers, they are likely to be similarly not helpful to you.
If the answers to the older question don't answer your question, it means there is something about your question that is different from the older question. Asking a new question doesn't mean re-asking a question that will also appear to be a duplicate. It means asking the question in a way that clearly differentiates it from the older one.
So to me, the blurb seems like good advice. But perhaps it should suggest clarifying the difference.
As for asking a new question instead of modifying the old one and reopening it: if it has upvotes, or at least no downvotes, by all means clarify the difference between your question and the older one and try to get it reopened. But if it has downvotes due to problems with the question that have been fixed, they rarely get retracted and they prejudice the question. You're better off with a fresh start.