Yeah, I'm not disputing that we get more fragile as we get older but I don't especially feel it yet at 37 (recovery from exercise takes a bit longer now though).
I guess my point was that 'park' doesn't automatically mean hucking ourselves off the largest booter you can find first time around. At any age it's no more dangerous than you make it. It would be a shame for anyone to assume it's no longer an option at [insert random age over 20 here]. Just as no one should assume park is mandatory for a snowboarder in the first place!
Personally, I had a load of fun doing 1's off the beginner kickers and some easy boxes. Pretty unimpressive but still fun. Am I going to go much bigger than that? I doubt it. Just be a bit sensible, focus on technique and ride within your(and your body's) limit.
And certainly don't think the fun stops at 30! I've had a total fkn blast in my 30's