>> How can something be both commercial and non-commercial?

There are different types of "commercial". For example, it's one thing to use it in a commercial render; it's quite another to sell the thing as part of a larger package. Some folks dont allow commercial work in the form of derivatives, like for-pay textures for a for-free product. Just depends on what you mean by "commercial", because it's not a one-size-fits-all definition when it comes to these things.

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