> You don't get why people would like to be in control of a powerful new technology

You will not have that control. Even if everything were open source. This is because you don't have 100 million dollars of compute.

There, the difference for almost everyone is negligible.

> Without fully end-to-end open source models you are still at the mercy of the model provider to keep providing updates

No. Because you can post train it. And even if you could train the whole thing again, but with slight changes, once again, you aren't spending the hundred mil in compute to change it only a little bit.

Instead, you'll do post training like everyone else does.