>

I would and I will! 
But more seriously, sometime you don't want to send whatever you wanna talk about for it to just sit waiting while you're dying of anxiety , because you don't know if the person purposefully don't respond or is just not available.
This but for IM at work. 
Them: “Hi”
Me: “Hey”
Them: “How ya doing?”
Me: “Good. What’s up?”
Them: “Do you have a minute?”
Me (in my head): mutherfucker you just took a minute with this bullshit. Just lead with that! >

I had the impression "hi/hello/whatever" was a common placeholder for "are you here right now to discuss something?"