In their keynote, they said it performed like a RTX 3080. They didn’t say only under scenario A it might peform like a RTX 3080. It was misinformation Apple was spreading during the keynote.
People are in their right to call out Apple on this.
As macOS has never been much of a gaming platform they are obviously talking about compute and not gaming. And it's not like the Apple M1 Max 32-core is not capable at performing on the same levels and beyond as he RTX 3080M but you need to have your games optimised for it.
Apple Silicon uses the Metal API. Unless you have your game or application using Apple's Metal API you won't be able to utilise it's full capability. Just like you won't get the best out of the CPU if you don't code using Apple Swift.
Just like you won't get the same level of performance in a game on Windows if the game developer is strictly using OpenGL4.6 instead of DirectX12 as it's incapable of using current-gen graphics card on Windows in any meaningful way resulting in you getting a crazy amount of performance overhead as a result.
As macOS has never been huge with games next to no game developer has used the Metal API as a result of Mac's have been lacking in graphics performance for years. Now we suddenly have capable graphics performance but as a result of no developer taking the time to have their games release on macOS using the Metal API they are vastly underperforming as a result of the games not being optimised for the platform at hand.
And most likely this isn't going to change, even with the move to Apple Silicon and Apple M1, M1 Pro and M1 Max because there is still no great market for gaming on macOS so developers won't waste time on re-doing their games using the Metal API as they won't get any sensible return for their time invested.
Productivity applications on the other hand, which is something that has been a huge market on macOS for decades are all going to utilise the Metal API going forward as not doing so wouldn't make any sense as all software not doing it will fall behind in performance and loose business to competing companies that will start utilising the Metal API.