Just because jobsjobsjobs.com.au can fund an ad campaign doesnt mean they are successful, and the real question is how much more successful would they be if they had jobs.com.au instead of a problematic domain like jobsjobsjobs.com.au, a domain that would have far less typos and traffic bleeds.
The guys at jobs.com.au get a lot of traffic without advertising, its all free seo and typeins.
As for the other local brand name job sites, they got in early, massive financial and traffic backing from the major media groups, their dominance has less to do with their brand names and more to do with their timing and alliances, these companies already controlled the job classified markets and brought that business online.
The job site industry in Australia has already been stitched up, jobsjobsjobs.com.au will continue to lag way behind the other players in terms of traffic and sales, jobs.com.au on the other hand has no overheads and just on sells their free traffic to jobx.com.au, they may never reach the lofty heights of seek.com.au but its still a great name, with a very profitable business model they have setup now, and will always be attractive to a range of buyers.
Jobsjobsjobs.com.au is not going to overtake or even come close to seek or mycareer etc, and when the ad money runs out the traffic will drop too. They've been running tv, radio and display ads for 2 years now and their traffic rank is still so low. If they had spent a fraction of that money on quality industry specific domain names with traffic they would be more competetive and less reliant on expensive and untargetted advertising.