Nobody is arguing that this might be acceptable for a couple of your absolute best prospects once you've seen them play a bit of senior football at a minimum, but we're talking specifically about Walsh here, or at least that's how it started.
To stop people taking to Walsh at barely 18 years old today, you'd need to have made this call back when he was 16 or just barely 17 and still in high school (he would have barely played much high level high school football at this point mind you) and if you're doing that sort of thing on a regular basis you're just not going to have a very high strike rate for success.
The gap between making a call like that on a 19 year old Fifita who is already playing Queensland Cup, and in his case NRL and State of Origin, is vastly different to doing it with a 16 or 17 year old high school student like Walsh would need to have to been in this example.
Yes, in broad strokes out recruitment and retention has been horrendous, but I think in the Walsh example specifically, it might be clutching at straws a little to suggest the Broncos needed to act more decisively at an earlier age.