Because they got pushed out by better players…
Let’s not kid ourselves…Surf gets tons of talented players. Produce or your playing time evaporated. Albion, Rebels and Sharks see many of the top players pushed out of Surf first teams.
Partially true, but also partially false. Some players get pushed out, yes. But I can think of at least 5-6 across those age groups (my kid plays with one of the 05s--not on one of the clubs you mention) who would still be starting there had they not left. You sound as if you're a Surf parent. If you have been there 5+ years and your kid in one of those age groups, then you should know about these players too.
I know it's very difficult for the Surf devotees to understand, but some players find a better fit elsewhere and thrive. It's a blow to the "Surf is Supreme" ego, of course, (to have a player leave) so the line from the club will always be, "they weren't good enough". But watch those players on the field now and your eyes will see the truth.
There were very legitimate reasons other than playing time to leave Surf over the past few years. Take the 2005s, for example, they had like 5 coaches over the course of three years, one of whom left under allegations of sexual harassment. The 2004s had their own set of issues with favoritism and politics being front and center with two of Surf's top execs having daughters on that team. And, if you get your wish with CB taking over the 2006s, won't they have had only two coaches for 8+ years? And you wonder why they might not be progressing? A control-freak parent group who won't let their kids be touched by Deza? (pure speculation, of course, but it does seem odd)
It's not just limited to Surf. Starting players move from Blues, Legends, etc. too. My overall point is that the notion that all players leave clubs --even the biggest--only because they're not good enough to stay is demonstrably hogwash.