Credentialing. I frequently find myself reading Tweets from people I’ve never heard of because someone who I know to be an expert in a particular topic has liked or retweeted them. This kind of signaling helps surface more obscure content and make it available to people who wouldn’t have found it on their own. This is a huge deal.

One important one is reposting that shows post to your followers who might not see the original. It is important way to see other content.

Also, liking it signal that other people were interested in the post. I don't global likes are useful for likes from people you follow are important.

Finally, replies mean can see interaction from people you follow. If you follow interesting people, you see interesting discussion.

With social media, it isn't possible to read everything, I know I used to try to read my whole Twitter feed. There needs to be some way to filter than just time when you looked. I think the current algorithmic feed is bad because it tries to show other stuff instead of ordering things that want to see.

"social" means people interacting - replies, likes, etc.

If someone has an RSS reader with feeds from some news sources, official channels issuing announcements, etc - that's great, but does anyone consider that "social media"?

(Of course, you can believe that social media is bad and you don't want it, but that's a different question)

For things like a missing person alert, it provides an instant feedback mechanism and the ability to share things with people you might know in the affected area.

Otherwise, there’s absolutely utility to interacting over social media. We’re doing it right now!

People seem to like it?

Why is information gain the correct metric?

We're talking about marketing here. Shouldn't it be conversions or awareness or something?

filter out unimportant stuff