I don’t think that would help. As long as the field is there, spammers will put stuff in it. I suspect they’re not big on following up and checking to make sure the link works.
]]>Weirdly enough there’s a way you can not have the names clickable whether they have a URL or not. You basically edit the comment-functions.php (placed in your child theme) that has the href in it.
If you want I can help you with that.
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