[bpodgursky]

> A tree planted in "dirt" will be about the same size 3 years later. A (young) tree planted in rich compost can double in size in a year

Rapid growth is not actually good for the longevity of a tree. A tree which grows rapidly (presumably to take advantage of a resource surplus) will be structurally weaker and die at a younger age to wind, pests, etc.

So it's true that planting in compost can accelerate the tree, but there's nothing wrong with planting a tree in "dirt" from a natural perspective (assuming it doesn't outright die from pH balance or lack of water etc).