Earlier quoted context omitted.
I ask candidates to list three blog posts that they recently read and enjoyed. Seems to be an easy way to filter out non-serious candidates and script kiddies. This has worked with roughly 60 to 70% of the candidates I have interview since I implemented this rule.
Does whether or not they are relevant blogs to the role or industry matter at all to you? My gut feeling is that you would get a better read on the personality of a candidate when they send you links that have little or nothing to do with the job they're applying for. All three links to industry-relevant blogs will tell me is that this candidate aims to please for obvious self-advancement reasons.
You're right that it gives me a read on the candidate based on what they share. It's a good filter - if the candidate picks something really basic to share, it shows how well they know their tech. If they choose something more advanced but can't contextualise it, that's a sign that they are faking it to make it.
Three industry related posts isn't automatically a red flag to me because the posts may cover different sub-topics.