Using call-to-action or primary buttons to show status of form completion instead of form UI element

I noticed this while using a form to submit some information that the nature place where you indicate the status of the transaction isn't being used but instead the call-to-action or primary button is being used for this instead:

So in this example, a progress bar is being used to show the status of a document being attached but it is the call-to-action down at the bottom of the form that is displaying the status of the transaction (with the button being grayed out at the same time).

I think that it is rather ambiguous to have a call-to-action button showing the status of a process but also indicating its own status at the same time.

Is this a common trend to use the call-to-action button to indicate the status of a step in the process rather than the status of the action transaction or action when you click it?