I have just surfed knee high onshore waves by myself and had fun. I had some time to think about this question as i have on numerous surfs with all types of craft.
I am 52, 6'3" and 100kg and mainly ride a 6'3" webber minifish. It goes great in crap waves and is suited to very small surf. My biggest board is a 6'10" Simon Anderson which goes great in overhead waves.
There are so many boards around for fat old guys like me, why would anyone want to ride a 9ft long board that you cant turn in tiny waves and when the waves are good why not ride a high volume short board?
Is it that these longboarders have just given up on short boards because they are crap surfers? Mark Richards, Simon Anderson, Rabbit are all older than me but ride shortboards. I have a metal hip replacement so its no excuse that your body is not up to riding a shortboard.
Is it the nostalgia of riding the first surfboards, why not then drive a 1968 Holden with no power steering? I like 1975 single fins but i would never ride one in decent surf as my first choice. Maybe 62mac can enlighten me?

Tell or show us what you are riding, picks ect.