Ed Yong distills the notion of self-promotion through social media in one sentence:
The way to think about this is to map any [online] behaviour onto the physical world.
And here is the explanation in full:
So, would I tweet about something I wrote. Yes. That is basically telling friends about something I did that I’m proud of. Who wouldn’t do that in real life?
Would I tweet about something I wrote multiple times? Yes. In the same way that I would tell the same anecdote to different groups of friends. Different people are online at different times. If the same person happens to hear the same anecdote, who cares?
Would I tag friends into tweets, or DM them about it? Rarely, but sure, why not? Same thing. This is just specifically going up to someone and telling them about something I did that I’m proud of. I’d wouldn’t do this for everyone, but for people I have an established relationship with, why not? I wouldn’t rankle if someone did it to me.
Would I tag strangers into tweets? Probably not unless under exceptional circumstances. Would I tag a group of influencers into a tweet, many of whom I’ve never spoken to before or follow? No. Hell no. That would make me the guy at the party who only goes up to the famous people and shouts loudly about themselves. Who wants to be, or speak to, that guy?
Would I reply to the tweet of someone I follow but have never spoken to, alerting them about a post I wrote that was related to what they tweeted about? Absolutely. What, you’ve never started a conversation with a stranger riffing off of what they said?
It is social media. Online, too, the same rules apply.