system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why all the obviously 'bot internet comments without URLs?

Over the past several years I've noticed that there are a lot of blogs with almost no comments, except some that are so vague as to be useless ("I love your blog I want more see"), "WOW", or obviously randomly generated.  None have URLs.  Are these comments that had the URL filtered, are they trying to build some sort of "cred" so that they don't get autoblocked on other blogs, or something else?  Thanks!
gpt
Sometimes it is about cred, sometimes it is about testing the defenses of the comment system to see what gets through and what doesn't.  In many of the cases, if you checked the same comment a month later, there would be a link; comment systems often allow you to edit your own comment later on without the same intensity of auto-moderation.  Sometimes, also, the spam is trying to game search engines... there may be links hidden in the text that are not intended for you.