Itoje is a poor example for making the argument to blood young players in test rugby for the sake of them being young players. He was by all means a very developed professional rugby player by the time he ever stepped foot into an England camp.
If anything it was a slower blooding process through the England U18, U20 setups (which are much better than what Australia has going on at that tier of play right now) and finally the premiership before he was selected in an England squad. He was outstandingly dominant at the lower levels over a course of years and then continued this form through his time in the Premiership.
How many of these young Australian players can you say that for? How many of them dominated their international opposition throughout their U18-20s careers and then carried that dominant level of performance through seasons of Super Rugby? How many were leading a nearly undefeated team at his age, completely on merit and ability?
He's one of the best young forwards of any generation to date (so by all means a huge outlier) and even then was not just thrown into senior test rugby because he had a few good moments over the course of one domestic season.
Itoje was all but a surefire thing when it came to test rugby and those types of players are not the norm regardless of age.
Even the All Blacks blood players at all kinds of ages - you can see this happening right now. Let's look at the guys they've blooded into the squad since May of this year:
Ofa Tu'ungafasi - 24 (Pro since 2012 - 26 caps for Auckland, 42 caps for Blues)
Elliot Dixon - 27 (Pro since 2010 - 56 caps for Southland, 65 caps for Highlanders)
Ardie Savea - 22 (Pro since 2012 - 31 caps for Wellington, 49 caps for Hurricanes)
Liam Squire - 25 (Pro since 2011 - 38 caps for Tasman, 14 caps for Chiefs, 13 caps for Highlanders)
Seta Tamanivalu - 24 (Pro since 2012 - 37 caps for Taranaki, 22 caps for Chiefs)
Damian McKenzie - 21 (Pro since 2014 - 21 caps Waikato, 33 caps Chiefs)
None of these guys are teenagers and in fact they all have pretty considerable experience with top flight rugby already. All of these guys played ITM for 2+ seasons, a competition that is frankly better than anything Australia has to offer young players at that level/age right now. They all played at least 2+ seasons for Super Rugby franchises which are far more successful than their Australian counterparts in general (with the exception of Blues) and regularly produce more well-rounded and skillful players than our franchises have in recent years.
These guys are getting blooded into the ABs at a point in their careers where they are simply ready for it - on an individual level their players are just better than ours and that's largely down to more regular exposure to a higher level of competition beginning at a young age. Even after being blooded their involvement in the side is methodically managed until they've done enough to lock down a jersey of their own.
The AB's are able to blood these younger guys because their succession planning is better than ours, their players are better than ours, and their sub-Super Rugby competitions are better than ours.
Absolutely none of them are thrown in just because they are a promising young player at the beginning of a RWC cycle, there's far more that goes into it. The same must be said for the Wallabies, for these young players to be successfully integrated into the side a similar approach must be (and in many ways is) used. Where we seem to fall short is that our players still have some pretty glaring issues and faults in their games and this largely boils down to a relative lack of high-level competition exposure for many of them at younger ages (we're just really coming into the generation of players who will be moving up after multiple seasons of NRC exposure before Super Rugby/Test rugby), issues with skill development amongst these same players, and a lack of depth in Australian rugby overall.
This isn't even to mention how wildly different the demands on the bodies of young players are in Union v. League (or a comparatively powderpuff game like AFL for fucks sake) simply due to the fact that rucking is a part of our sport. Putting a guy in before he's reached physical maturity can have far bigger repercussions in Union due to the nature and frequency of the contact in the sport - and not every player matures at the same rate.
The only way to properly manage the involvement of young players in Australian rugby for the Wallabies right now is on a very individual basis and not because of some sweeping generalizations about how the All Blacks, the Bulldogs, or anyone else does it. We have our own unique obstacles to overcome in this department.
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