Where does that come from, given that the original 3LBB had no mention of any "Third Imperium", unless you also bought the optional Spinward Marches supplement? And pretty much every edition of Traveller has had rules for (sub)sector and world generation, which rather implies that you're expected to create your own setting instead of using some kind of official Traveller universe. I would expect a bunch of ancient Traveller grogs to remember where things started.
Yea, that post didn't parse right for me. If it's claiming Traveller MUST equal Third Imperium, then I call BS. But of course there is a strong contingent of folks who seem to feel that way...
Sorry about the lack of clarity. I was ranting, plus I rewrote parts of it multiple times and some of the rewrites may not have fit together all that well.
What I was trying to get at was that a lot of the people in the "Traveller == 3I" camp present themselves as having been playing Traveller forever, even though, in the earliest editions of Traveller, the 3I only existed in optional add-on products (such as Spinward Marches) and didn't get so much as a passing mention in the core rules. "Traveller MUST equal 3I" is clearly bullshit because there was a time when there was only Traveller and there was no (published) 3I.
On top of that, they're also ignoring the ubiquity of system and sector generation rules across most/all editions of Traveller. Maybe it's just me, but devoting a significant portion of the rules to "here's how you create your own setting" seems like a pretty strong indication that you're intended to actually use those rules and create your own setting, not go out and buy existing 3I materials.
So, in summary, I agree with you, plus I think the "mandatory 3I" crowd are a bunch of big, stupid poopy-heads who can't see that the game itself clearly disagrees with them.