It is reasonably common in London. The SID restriction is just to make sure that no-one climbs above that level without clearance. In AUS, your ATC clearance specifically states your cleared level, ie 5000ft. In other countries they do not give you that level, it is per the SID, which is why they have the Below limit on the SID. Just a different way of doing it.
It is reasonably common to get held at 5000ft on the MARUB departure, and it can be until out at MARUB, which is a bloody long way towards NZ considering you are probably going to Melbourne
It is because arrivals are held at 6000ft (which is why the STARS usually have an above 6000ft requirement if they go near the departure tracks (eg BOOGI).