There are two aspects to your observation, Michael:
1. The behavior of the CTA button
2. The position of the progress bar
Ad 1.: I'd consider the message on the button to be an explanation of why that button is currently disabled.
In "earlier web times," ;) the confirmation button would not be disabled. If users got impatient with the upload — or, more generally, the lack of progress —, they might click that button several times. That could potentially result in triggering the action multiple times, which is especially annoying in a payment transaction.
Nowadays, sites will often disable the button to prevent such multiple clicks. Without context, though, the user might not understand why the button is disabled. Stating that reason right on the buttom provides meaningful feedback.
Depending on the size and complexity of the screen, providing that info on just the button might suffice, or it might make sense to provide additional progress feedback elsewhere on the screen.
Ad 2: The placement of the progress bar is a judgement call, IMHO.
If multiple documents can be uploaded to the site shown in the screenshot, it might be helpful to the user to see upload progress for each document. Then again, maybe a single, "summary" progress bar would have sufficed here, as well.
In the latter case, I'd have placed it to the left of the button.
That's because, once you've completed the form, you've now arrived at the bottom of the page. And clicked the button to submit your input. So why force the user to look higher on the page to see additional status feedback?
P.S.: As for Aleks's suggestion, I agree that this treatment of buttons has become common these days. While I find the progress spinner inside a button OK, though (although it took me a long time to get used to it ;) ), I would not display a progress bar inside one.
A spinner indicates just two states: "active" and "done." It's easy to distinguish between the two by just seeing whether the spinner is there, or not.
In contrast, a progress bar provides more precise data: it shows the actual progress, and the bar also reflects the speed with which the process is progressing.
Most buttons aren't wide enough to provide sufficient space for the progress bar to be easily "digested" by the user, and an overlaid label makes it harder yet to take it in visually.
So if the precision of a progress bar is required, I'd place a dedicated one in the vicinity of the button.