If you actually have a read at the whole thread, you’ll see that @tr909 is only talking about what could be considered a flaw in design, especially compared to the whole gang of machines.
In such context, your remark was a bit missing the point, and slightly uncool.
But if you stick to your position, so be it.
Going out of the way to get offended is uncool too, goes both ways. Though everyone can take a moment to consider that tone of conversation is the weakpoint of any online discussion.
A suspicious mind could think that it was a faux pas during the manufacture of the mkI, like a PCB trace not connected or routed wrong, because it may not appear to make much sense, so rather than scrap a whole production run, it was turned into a feature
A more rational possibility is that the Octatrack was designed for DJ/Live use and it was deemed useful in the the design process to have a way of monitoring cue outputs independent from the main outputs without having to have cables connected to the cue outputs.
A better solution would have been to have 2 volume controls, one for master outs, one for phones/cue.
Still, once you get used to it, it isn’t really an issue.
Even if you don’t cue tracks dj style, this knob is a godsend if you use outboard effects - just hook them up to headphone outputs and at the mix page set the knob to 100% cue. So you get a knob which is a master send to outboard fx, super useful as you don’t have to click cue on/off on several tracks