Well, maybe so.
But I disagree with the entire mindset that says only one person can work on a tree for it to be "theirs".
Let's choose another venue, say, painting.
Does the artist have to make his own paints? Sure he mixes his purchased paints on his pallet, but he didn't make the paint! How about the canvas? Can he purchase stretched canvasses at the art store? Ok, so he builds a frame and stretches his own canvas. Happy now? Whoops! SOMEONE ELSE made the canvas! Someone else cut down the tree to make the frame! See where I'm going with this?
Even yamadori bonsai has "Mother Nature" putting in design work. The bonsai stylist didn't do that.
Bonsai is different. The media charges over time. Trees cannot remain static. Even if only one person works on the tree, the tree changes. Some branches grow, others die or wither. If a branch dies that the owner really didn't want to die, but he restyled the tree, should he take credit for the restyle? It's not something he wanted! But, stuff happens!
Let's say I buy a tree from Joe. Joe pruned it, wired it, whatever. But, I didn't like what Joe did. I turned it around, removed all of Joe's wire, completely changed the style do that it was unrecognizable. Should it still be considered "Joe's tree"?
Here's an example:
As purchased:
View attachment 142939
As restyled:
View attachment 142940
Are you really going to say I can't take credit for the styling of that tree?