I keep seeing articles about this. These ideas seem to get hatched and then spread like viruses.

There’s absolutely nothing wrong with disabling a button when clicking on it should not occur. As long as you have some kind of visual cue that the button should not be clicked. What’s fundamentally important is that it’s made unequivocally obvious to the user that the action the button triggered is in progress. This can be something as simple as changing the button text from “submit” to “loading” but other common methods include using a spinner icon, dimming the opacity.

Another option, and one I actually prefer is to use a full screen overlay with a black semi opaque background and a nice loading animation. This renders the entire page inaccessible preventing a user from potentially navigating away while a form is submitting by clicking on other links on the page.

Your argument about disabling buttons negatively impacting screen readers makes absolutely no sense, I’m sorry. Why would a screen reader be reading the screen while a form is submitting?