I've seen more than one. In fact, one of the things I noticed when I got back into bonsai after spending, essentially, twenty years away from it, is that in the interim, there seemed to be a shift away from prizing the no-scar, trained from seedling tree, which was a real badge of honor and indicator of experience and skill when I was first introduced to bonsai in the early 1980s. When I first got into it, I remember a sizable minority of older bonsaiists who, instead of warning people that their method would mean "you spend the first 20 years achieving nothing", would scoff at the people who used what they thought of as a cheap and easy method of chopping back, leaving ugly scars that can never be fully hidden. They preached patience and would remind us young guys that nothing truly worth having could be achieved in a mere five or ten years, as they showed off their 40 year old black pines with no pruning marks bigger than a pencil eraser. You almost never hear people talk like that anymore, and you rarely see a tree of any note that hasn't been cut back severely.
Having still retained some of that programming from the early 80s, I do have a lot of stuff grown from seed or saplings in my collection, but I've only been back in bonsai for less than four years, so they are all still sticks in pots. I like the fact that they started from nothing but a little seed, but the progress is very, very slow. I'm probably not going to live long enough to see them become great trees. And with some species, it's ridiculously slow and not worth it. I tried growing needle junipers from seed. Few took, and the one (out of 25 seeds, IIRC) that made it is two years old now and about three inches tall. A cutting I struck at the same time is now two feet tall with a trunk that's over half an inch thick. I'll never waste my time on juniper seeds again. Other stuff is great, though, especially trident maples. Growing those from seed is fun and they progress reasonably quickly. I have plenty of those, grown from seed, that would be snapped up quickly at a club raffle.
I'd never thought about or noticed that. Are those varieties completely seedless, even if you grow them in the ground for 10 or 20 years?