This has the advantage of allowing you some creative control over your reference, and also reducing their workload. Prepare a draft or template of your recommendation letter that makes it easier for your referrer to edit with their own ideas.
So, this could be a safeguarding measure against them not finishing your recommendation letters before the deadline. There is always the possibility that the person you ask for a reference ends up not having the time to do it, or they simply forget. Ask double the number of professionals for a letter of recommendation than your university asks you for.
