Actually, confusion about that message was the topic of that
old thread I referred to. The poster wrote "... my depth of what? Level of 'Re:'? reputation?". I really shouldn't take someone else's argument because I actually didn't find this overly confusing myself (for whatever reason) but the point is not everyone will read the message the same way.
The ability to change the level isn't contested (of course). I'm only suggesting that the initial reply depth could be set higher (or infinite) until the user has the experience and desire to filter away long-winded debates (such as I'm starting here ;-). Perhaps it's not really necessary, as you suggest, but is it actually bad in some way to make this change? Will it lead to more or less confusion? Don't know but I have my opinion.
Before it seems like I'm getting too carried away, I do realize that this isn't a terribly important issue. It was just an idea that at least some people might think of as some small improvement.