Feature suggestion: a countdown so you know how many more times you and someone can reply to each other before you hit the limit and have to start repeatedly editing your last comment to carry on the conversation.
Do you have more info on the max comment depth by any chance? I did a quick search and, unless the info is outdated, it looks like there's some kind of anti-flamewar mechanism in place, but no set max depth https://news.ycombinator.com/item?id=11429230
I couldn't tell you if it's a set depth or some kind of stochastic system. Many of HN's rules are subtle/invisible, to the point you can't even be sure whether they're being applied by an automatic system or by a moderator. For example, you can post a large number of highly-upvoted comments in a short timespan, but if their score is neutral or negative you'll get muted for an indeterminate amount of time; I've seen between ten minutes and a full 24 hours personally. You can also get muted for stepping on the wrong person's sacred cow; you can tell when that happens because you'll find yourself muted when your last day's comment history is, say, only three comments and all of them have positive scores and no flags. I've found it handy to keep a list of "things mods don't like opinions on".
