alt Hacker NewsMicrosoft OneNote had this back in 2007 or so, granted the speech to text model wasn't nearly as advanced as they are now.
I was actually on the OneNote team when they were transitioning to an online only transcription model because there was no one left to maintain the on device legacy system.
It wasn't any sort of planned technical direction, just a lack of anyone wanting to maintain the old system.
I remember trying out some voice-to-text around 2002 that I believe was included with Windows XP.. or maybe Office?
You had to go through some training exercises to tune it to your voice, but then it worked fairly well for transcription or even interacting with applications.