While I agree, in a good world with coaches paying attention, the Rule 5 draft is mostly worthless, there are benefits for a newbie (if the intent is to help the newbie)
the rule 5 draft gives a newbie their first glimpse into how the draft process, player ranking system works, gives them a chance to experience a "draft" so they'll have time to ask any questions that might arise regarding the process prior to the regular draft.
the rule 5 draft gives a newbie the sense that paying attention to the minors is important, paying attention to which prospects should be desired in the system, and which ones don't make a difference.
the one thing I don't like about the rule 5, which may or may not mimmick real life, but if somebody drafts my 41st player in the Rule 5 in the 5th round, then decides they want to return him the next day. Despite never having appeared on a ML roster, that player now makes $327k as opposed to the $57k or $38k he may have been making in my system. Perhaps the guy is nothing more than AAAA insurance, and sure the amount of money involved is peanuts, but that doesn't mean I have to like that a player got a $250ishK raise just for changing hands for 24 hours.