Question Sources are not Question Details, and they aren’t a substitute for Question Details. Sources may be triggers for a question or context for a question; they are not an elucidation of a question, a reason for asking, or a framework for the kind of answers sought.
They’re not useless, but they’re not useful as often as details are. The fact there’s only one of them allowed can be a problem too. Compared to the free text of the detail, Sources are (by design) a straitjacket. So I anticipate that I will use sources less often than I used details.
I anticipate they’ll mostly be dumping grounds for YouTube links (which may be relevant to the question), images in image identification (and good luck wording that question usefully), and links to news articles for current affairs questions.