Yes, those "ORs" are there because there are cases where candidates right out of highschool have been accepted onto their program.
In regards to university, there is NO disadvantage in completing a degree first. It contributes to personal development - I think they really value maturity, independence, life experiences...etc etc. As a matter of fact, if you look in the LONG term, the 3-4 years will probably serve you well.
Also, completing your degree can't lower your chances