this wouldn't be so bad if it weren't for the fact that you often have to follow a link to expand the tree, that you then have to back out of to get back to the main thread. I have 16GB of RAM and a 27" screen. I can handle expanding a tree of text inline.
I don't follow. I just opened a random comment thread, and counted comments being shown up to seven levels deep (which was the deepest comment.) Is the behavior you describe only if you're logged out or something?
Try opening your link in an incognito browser.
If I go to the link posted above [1], I first see a much narrower window (careful, don't click on the black area to the sides, or you'll go back to the subreddit, the whole thing is basically a modal dialog now). Then I see one single comment, and it itself is half cut off. Below it I see a bunch of "related" content: https://imgur.com/a/tyaheDC
If I click the button to expand, I see no comments deeper than two deep: https://imgur.com/a/HDlNYFK
To see deeper any any thread, I have to click a link which doesn't expand the comments but takes me to its own link thread. To get back I need to use the browser back button and my context is lost.
They do not want users to engage with existing comments at all. The first comment is half cut off. The rest are hard to get to. They appear to want you to consume the posted content, and maybe post your own comment if you like.
I don't think this is right, unless there's an "old new" reddit and a "new new" reddit. Old reddit doesn't have the alien avatars, or the lines indicating the thread. Also, the usernames are blue, and it looks entirely different in numerous other ways.
What I suspect you are comparing is the logged out experience and the logged in experience.
The difference is that I open the threads in a new tab, instead of just clicking on them. Also I am logged-in (so no related content below) and I have an ad blocker.
This typically happens if you google something and the answer is on reddit.