> I'm also not seeing the reason behind keeping the focus on the submit button when you can't interact with it now.

So let me complicate this a little bit because we're not talking about an immediate focus-change. It's not that a user clicks submit and immediately they should jump to the error field, there is a period of time where the form is being submitted and that's the only thing happening.

The question is, where should the focus go during that period?

Currently, if you do error-focusing then unless you also program handling for the progress event (which we'll get to below) what happens is the focus is on the button, then it's on the document, then it's back to the error. What I'm suggesting is that's pretty jarring, and it seems like the focus really should stay on the button until the developer is ready to move it elsewhere.

And you can move the focus anywhere else you want whenever you want, that's already easy to do, but if you forget to do so and you forget to account for the focus change, then dropping the user focus and throwing it onto the document is a really bad failure state.

And even if you do have progress-bar handling, for example in your fadeout example, if an immediate removal of the form is jarring to a visual user and they need a transition to make it more obvious what happened, then I would argue the same is true for a visually-challenged user.

While your form is fading out, maybe add an aria-live message that says submission is in progress, and by the time that message has finished being read out to a screenreader, the form will probably be finished fading and then you can move the focus wherever you want (assuming there is a good place to move it) and just remove the form from the DOM normally or set it to invisible in CSS, no extra attributes needed. This ends up being basically the same outcome as what you suggest, but I don't like this idea that we're going to kick focus to the document while we're waiting to put it somewhere else, and I don't like this idea that the browser is essentially saying "unless you have somewhere else better in mind to put the focus, then tough luck there is no focus anymore."

I buy that you might have situations where it makes sense to move the focus. I don't buy that outside of those situations the best default behavior for a browser is to drop the focus entirely and move it to the document. And while I'm more open to the idea, I also still sort of don't buy that situations that require visual transitions to improve UX for sighted users are good examples of when we should move focus immediately before giving a non-sighted user any feedback or heads up of what's happening.

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As a side note, I do want to re-emphasize again as well, buttons are used outside of forms. If we want forms to push focus to the first errored field by default whenever a submission finishes, that really ideally would be default behavior for the `form` tag, not for buttons.

Form behavior should really not be dictating how focus events get handled for disabled buttons. The question is whether there's ever a use-case for focusing a disabled button (in or outside of a form) because right now it's impossible to do so. We can always get rid of focus from a button, but we can't put it back if the browser prevents focus entirely, so unless we're completely certain that we're never going to need to focus a disabled button, I don't think it makes sense to design an attribute in a way that forces that behavior.