Full explanation here: link
tl;dr – (too linked, didn’t read) when you send someone a link, odds are they aren’t gonna click on it. You should always provide a summary, or notes. For example, in the link above, it goes right back to this page. Did you click it?
While this is likely true when you send a link to a few individuals, it is vastly more true about sending a link to a group of people. Email lists are even more impersonal than email, and the amount of responsibility people feel to take action based on something sent to an email list is microscopic.
It’s just a matter of recognizing the limits of people’s attention and trying to conform to them, much like “Don’t make me think”.