Replying to your point has, in some small way at least, broken the flow of the discussion stemming from the OP. Only you should get a notification that I've replied to you, not everyone following the thread. Im replying to YOU and your points, not the people who replied to OP or OP. Its very natural and far more human to take you aside (without the burden of creating a DM), and not derail the main conversation.
We can disagree about what is good UX or not I suppose, but its at least my opinion that generally speaking this type of ux is now a solved thing and there is no reason not to support it. XenForo or any software thats been maintained for 10+ years may have arguments against it such as resources or lack of energy or will, but there really are not too many other good reasons. Simply look at just about any major long form and many short form discussion platforms that are mainstream. Any comments system, slack, discord, reddit, they cannot all be wrong.
Back to on topic, and I have to state as such since the conversation is linear...we can say silly things like "forums are not reddit or are not social media" but this is simply a ridiculous argument. Reddit is almost exactly a forum, if you ignore the size of it and a few other liberties. Its just a very very successful one. And social media is effectively just hyper optimized engagement platforms, which forums would benefit by learning from. We can debate this another ten years but its just simply misinformed. Many things can be true at the same time. Forums need to be highly engaging (a la modern social platforms) , offer new ways to interact with others such as short form discussion, all while maintaining traditional long form discussion support.
Strong disagreement about most of this, really.
First up, notifications - yes, I got a notification because you quoted me. The only other people who got a notification are those who opted into notifications for the whole thread (or possibly the whole board, though that seems unlikely). But the reality is that it’s not really a derailment - it’s a set of related observations that continue the discussion. That’s, well, how discussions work - they ebb and flow and meander as opinions gets added.
Slack and Discord both have the threaded nature except 1) each channel in both is free flowing, threads are explicitly a derailment of a specific conversation, 2) good luck finding those threads again in any even remotely busy venue, 3) good luck if a thread is opened in the wrong place, 4) Discord forum threads aren’t even available by default, you have to explicitly go through a bunch of hoops to even enable them suggesting even Discord has reservations about them, though regular threads exist and almost no one uses them anyway.
It would be a very different argument if these were
every discussion on those platforms, but they’re the exception rather than the rule, and even then they have major UX failures that make them suitable for specific occasions rather than general use. (I say this as someone who has a work Slack where I have to read every message, and am an admin of several Discord servers including multiple that have the forum feature enabled, and frankly… no one likes the threads, the forum feature is preferred and that just spins up a number of linear threads and no need to have threads inside them.
The UX is certainly not solved - Discourse tried to reopen this debate quite firmly when it debuted, both in terms of “that’s a branch of conversation, open a new topic” and it’s one singular level of nested replies, and the pushback including from long-standing fans of threaded conversation was overwhelmingly “your UX is broken”.
I put it to you the other way: if threaded replies were in such demand, there would be every argument to implement - but it really isn’t in the demand you think it is, because there are new forum platforms coming out that also don’t implement it. If it were such a thing, why is no-one implementing it? Because even the very newest forums don’t have it, nor plan to implement it.