You named anomalies in bbing, those aren’t the norm
Now compare with all the other O winners and pro competitors
I did.
A number of bodybuilding legends have lamented about the lack of teenage bodybuilders coming up through the ranks, like the Shawn Rays, Lee Haneys, Tony Pearsons, Dennis Newmans, and other big names from days of yore.
Phil Heath is the only guy off the top of my head, who turned pro in his early/mid 20s.
Here's a brief list of guys who were somewhat long in the tooth, when they turned pro.
NPC Nationals Champs
Johnnie Jackson - early 30s
Toney Freeman - mid/late 30s
Matt Duval - mid 30s
Bill Willmore - mid 30s
Ed Nunn - mid/late 30s
USA Champions
Bob Chicherillo - mid 30s
Quincy Taylor - mid 30s
Idrise Ward-El - mid/early 30s
Desmond Miller - mid 30s
North American Champions
Jeramy Freeman - early 30s
Marcus Haley - mid 30s
Michael Lockett- early 30s
That's just a small sample. When you factor in the class winners that turn pro at these shows and the Masters divisions, that's a LOT of 35+ dudes entering the pro ranks.