>

This is relatable. If they only text “hi” I feel obligated to continue with a “what’s up” or “how’s it going.”
In reality I really don’t care, that’s why I didn’t text you first lol
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?" >

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. >

Which is, as I said, the implied meanning of "hi/hello". >

Do they need to have a point or question? People just want to chat sometimes. >

but even "hi" isn't chatting. it's just a greeting. a better opening for a conversation would be "some weather we are having?" or "did you catch that hockey game last night?"