I'd say in Traveller it amounts to whatever fiat the group agrees on over choice of which characters they go on to play. The rules offer slightly contradictory notions about that. In one place it saysWell, with the more traditional versions of Trav, you could simply argue that even using the word "build" there is questionable. The degree of steerage you can conduct with generating one of those characters is, to be charitable, rather limited. (This is in contrast with something like Cepheus Deluxe where it might be possible after a fashion, once you decide what function the character is going to play in the group).
it is possible for a player to generate a character with seemingly unsatisfactory values; nevertheless, each player should use his character as generated.
but immediately goes on to suggest that
Should a player consider his character to be so poor as to be beyond help, he should consider joining the accident prone Scout Corps, with a subconscious view to suicide
This idea of "so poor as to be beyond help" is a nod toward prioritising optimisation. I think a position that robustly upheld that the two are never incompatible would have ended the paragraph at the earlier sentence.