Here's the logic since it's not that hard.

Say Parent Co. controls Subsidiary LLC and owns 60% of it. Minority Corp. owns the other 40%. Subsidiary LLC loses $10 billion.

Consolidation accounting requires Parent Co. to report the full $10 billion loss, as if it owned all of Subsidiary LLC, which it doesn't. Then, on the next line, it attributes the portion belonging to the other owner (Minority Corp.). There are two lines and one loss. Nothing is removed and nothing hidden. This is the definition of disclosure, not obfuscation.

Note that the trigger for applying this is actually control, not ownership interest. My understanding is that OpenAI Foundation controls the public benefit corporation with 26%. And for an LLC, the loss split isn't automatically pro-rata by ownership. It follows the profit-sharing terms in the operating agreement, which is why the there's a Hypothetical Liquidation at Book Value method. Under an old capped-profit waterfall, nobody can verify the exact figure without looking at the operating agreement.

"I can't verify the split" is a very different statement than "it's unclear what this means."

Your "why" question: the reason it works this way is that consolidated statements are meant to show the business as an operating whole because that's what a controlling parent actually runs. You can't operate 60% of a data center or sign 60% of a compute contract. Every line (be it revenue, expenses, assets, etc.) comes in at 100% for that reason. The noncontrolling interest line then answers the separate question of how much of that whole belongs to the parent's own shareholders. One statement answers two questions (what does this enterprise look like versus how much of it is ours).

As for your "who" question, the answer is simple: the other equity holders. Again, OpenAI doesn't own 100% of the entity. My understanding is that Microsoft is one of the other equity holders.