At a wild guess, that you may upvote a comment that you support – but there’s a second part that you wouldn’t agree with. Or that people should split up their comments so that people can upvote/downvote individual parts?

I think OP is referring to comment where multiple talking points are made, but you can’t selectively apply your upvote/downvote to specific parts of the comment. You either upvote it all, or downvote it all.

So if I start talking about how pineapple is ok on a pizza, a downvote for this take also means you downvote how I’m trying to clarify OP’s message.

You would reply twice to the same comment, generally

My post tried to convey that most people do this:

[Original post by OP about COVID-19] Comments:

• User A: "COVID-19’s symptoms can vary from person to person, and the vast majority of people do not present life-threatening symptoms. This can make it easy to conclude that COVID-19 cannot possibly kill someone [edit: here’s a source that shows that many people actually believe COVID-19 cannot possibly kill someone: statistics.net]. This is an unfortunate situation, because trusting the science can lead people to use appropriate masks and reduce its spread. [edit: added the word “appropriate” thanks to User C]
  • User B: “Really? I don’t know anyone who believes COVID-19 cannot possibly kill someone”
    • User A: “I responded to you by adding a source to my original comment through an edit”
  • User C: “My niece used a cloth mask in the Prague metro and still got COVID-19. I suppose the type of mask matters.”
    • “You’re right! I’ll edit my original comment to reflect that.”
  • User D: “I’m sure you won’t reply to this comment if I say that I don’t accept science.”

and they don’t generally do this:

[Original post by OP about COVID-19] Comments:

• User A: “COVID-19’s symptoms can vary from person to person.”
• User A: “Many people think COVID-19 cannot possibly kill someone.”
  • User A: “My source for this is statistics.net”
  • User B: “Really? I don’t know anyone who believes COVID-19 cannot possibly kill someone”
    • User A: “I responded to you by adding a source to my original comment through another comment”
• User A: “Mask usage helps reduce the spread of COVID-19.”
  • User C: “My niece used a cloth mask in the Prague metro and still got COVID-19. I suppose the type of mask matters.”

The point is that we usually don’t split our points into many comments of the same level. Levels here refer to this:

• Level 1 of a comment tree
  • Level 2 of a comment tree
  • Level 2 of a comment tree
    • Level 3 of a comment tree
• Level 1 of a comment tree

When I say that we take that for granted, I mean that I don’t see people splitting up their comments in the same level. Neither do I see people talking about splitting up their comments. In other words, neither in practice nor in discourse do people split up their comments.

Edit: Rewrite for clarity

Well yeah it’s not like

Interesting. What makes you say that?