A model is not a product
Whisper takes audio and returns text. That is the whole interface. Everything else you associate with dictation is somebody's code wrapped around it.
Consider what has to exist between “Whisper is very good” and “I dictated this email”. Something has to hold a global hotkey across every application. Something has to open the microphone, buffer audio, and decide when you stopped speaking. Something has to run the model without freezing your laptop. And then something has to insert the text into the focused field of whichever application has it — which behaves differently in a browser, a terminal and a native text view — and give it back to you when insertion fails.
That list is the product. It is also the part that takes months and never quite ends, because every application handles focus and text insertion slightly differently.