That sounds kinda like first finding a name for a software project (or the final product) and then design the product around that name! :D
More like designing the storefront before designing the business.
Or getting a domain name before doing everything else.
It does sound silly, but it also points to shallow nature of YouTube content. If you don’t have a good thumbnail it’s going to limit the success of your video because some percentage won’t click on it. It’s just how it goes.