True. Prior to Carl Gustaf, however, Swedish royal protocol actually used to be very strict. Members of the Swedish royal family for example could only marry royalty (not even nobility !), or else they were excluded from the line of succession. Carl Gustaf himself descends from Queen Victoria of the UK both on his father's and his mother's side.
Nowadays on the other hand, they marry Olympic Games interpreters, personal trainers, English bankers, and reality show constestants. A fine example of Swedish social democracy !