> 1. that closed source models are more efficient than open source

Not a reasonable assumption for a variety of reasons.

> 2. Deepseek is served at a profit and not a loss

Not a reasonable assumption either.

> Why do you need to know the architecture? Just compare Deepseek V4's performance with GPT 4 and treat internals as a blackbox.

Because the internals are what actually matter and what drives inference cost.

It would be entirely reasonable to expect that GPT-5.5 has some sort of optimizations or changes to the architecture to make it easier to train, or to make runtime ablation easier, or to better handle large batches, or whatever.

Those changes, particularly if they are non-public, can easily result in worse inference performance than a comparably sized model without those changes.

> It is borderline conspiratorial to believe it this way.

It's not any sort of conspiracy. It's how land-grab tech companies have always worked. To presume otherwise is silly.