Oceania doesn’t have an auto spot. Their World Cup chances boiled down to a two-match playoff against a team like Chile or Honduras...basically a 50/50 shot.
In Asia, there are 4 guaranteed slots PLUS a playoff. The overall road is tougher, but the chances of World Cup qualifying is higher.
If Oceania had a fully guaranteed World Cup spot, I bet the Socceroos would still be playing in the Solomon Islands and Tuvalu every qualifying cycle.