From Dusk till dawn, you seem to describing yourself, a careerfo waiting for his first captaincy. You may see yourself as the master himself regarding heavy iron, but that is a trick we all can learn pretty quick.
Therefore it is not sure you will be a good captain as well.
For that reason companies take DEC when their fo's are not(yet) up to the job.
I would rather fly with a 10000 hr ex 737 captain on a jumbo, then a 5000hr just upgraded first time captain.
In the past, you would go back first to a smaller type as a captain and then go back as captain wide body, but I guess times change