I haven't checked this claim, so maybe it is true -- but I thought the most popular RPG around the world was 'Call of Cthulhu' by Chaosium. They already have a non-CoC version of their ruleset called 'Basic Role Playing'. Having no classes or levels, and being entirely skill-based, it seems like a far better match for Traveller than anything derived from 'Chainmail'. Call me a grognard, but if I was compelled, under extreme duress, to include 'class and level' into Traveller, then I would be looking for a team up with Iron Crown Enterprises, the same folks who brought us 'SpaceMaster'.
Spacemaster Companion (1986) from SpaceMaster (SpaM) 1st edition included a life path optional ruleset... sadly, it didn't give a full set of them ready to use, just an exemplar. Section 24.1⋯24.2, pp 77⋯80.
SpaM is a bit more complicated than CT, MT, MGT1, or MGT2, and the current edition lacks that option...
Then why the collective apoplexy among the TTRPG community when they thought WotC were coming for them? Mongoose took a lot of flack from the C.E. crowd and there are some of them that will have nothing to do with Mongoose ever again.
All a misunderstanding?
No. The WOGL 1.0a license text is copyright WotC, and WotC can, in theory, withdraw permission to use it. In so doing, any license requiring its inclusion then becomes unfollowable and thus unusuable. By sticking to the Wizards license, they were very rightly concerned that Wizards could effectively end the legality of the Traveller Compatibility Licenses... And it wasn't just the Traveller/CE community facing that... any of the various d20 and 5e derivative works using the Wizards Open Gaming License 1.0a were facing that same potential doom.
The CE community is skittish about CotI even being owned my Mongoose because Mongoose wasn't decisive nor quick in response, and (from what I've seen as an admin on COTI) not providing an alternate license for MgT 1e SRD.
In Re T⁵ vs T5E
The T5 vs T5e issue is totally different - it's trademark, not copyright, which is a wholly different kettle of IP laws. Note that US Trademark laws are quite directly cribbed from the era of King George Ⅲ of England, And it's a case where, since Marc sold the Trademark last year, the brand confusion is entirely Mongoose's issue to deal with; besides T5 isn't the actual Trademark, IIRC... those are
T⁵ and
Traveller⁵ ... but I can see ill informed newbs «bleep»ing up the distinction... not like T⁵ has a terrible large body of works to confuse.
"T5" is an informal fan term, but it is a point of confusion already.
Building one's own setting is a fairly advanced activity that takes a lot of preparation. Play Charted Space, or detail hundreds of worlds, governments, political conflicts, trade systems, and wars yourself. Play Dune, or figure out centuries of scifi history and culture yourself. Some people, including me, like to do that. ]
A quite playable setting can be a subsector or two in size. At least a half dozen groups (only one of them mine) have use my Elestrial Concordat setting, at least that I'm aware of - yes, 5 people have told me they have used it...
The setting itself took about 20 hours of work of mine outside the two prep sessions, plus the 7 players & I some 5 hours (1 session) for setting, and 1 for campaign PC/NPC generation. It helps that we capped TL at 10, used MGT1 alternate world gen, and the basic writeups of the concordat systems were player done.
http://aramis.hostman.us/ec/body.html if you want to look. Or use. I don't have the deckplans of the one ship class with them... The TP-BX Patrol Corvette.