Collect nebari... nothing else matters.... is a rookie way to look at yamadori. With yamadori - TRUE yamadori... that's the one thing given a lot of latitude. If we only collected trees with great nebari, some of the most famous collected trees I know would have never happened. Because of their general age... yamadori doesn't require nebari by any means. I only mention this because there is a difference between the youngish tree which has been collected here... and true yamadori - which this is not. I don't want people (newbies) to confuse these facts.
But you are correct that nebari (surface rootage) is a crucial factor in suitability for most people to concern themselves with in general, when selecting material from any source. If it's there you save years of work... if it's not you learn how to develop it.
I will also say that giving oneself a pass that killing trees is ok and has no impact, is a very rookie thing to think. I find callous indifference to the value of life disturbing to be honest. I don't want people to be frightened that trees die so they quit... but there is a loss, and a breach on your part to nurture them when they do, that fact should not be dismissed out of hand. I think that must be a level of difference in practitioners... when you realize what you've gotten yourself into, and you mold your life to meet their needs.
I am saying this with all respect, and this is only my perspective. I'm pretty passionate about the sacred obligation between artist and tree. Neglect is a sign of tremendous disrespect for the art and life. Value nurturing the tree and the tree WILL reward you with beauty.
Kindly,
V