If you have ever received obtusifolia seed from me, they were also from wild trees.
I try to collect a small number of seeds from the largest number of different trees as I can. My opinion is that it's important to preserve as much diversity in phenotypes as possible, and taking 5-10 pods off each tree that is bearing hundreds is as minimal of an impact as I can manage.
Also, and I know the birds have to eat, if I didn't collect these pods, 95% or more would be eaten by cockatoos within a week of them ripening. Of the remaining seeds, less than one percent would ever find suitable conditions and germinate. Even less would survive their first summer. I do take young plants back out there to replant amongst their parents so I am trying to give them as great a chance of survival as I can, apart from spreading their territory to your backyards.
Bark rippers are killing a lot of these trees, and they need all the help they can get.