I'm kinda losing thread of logic here... It's not really clear to me what "progression" is in Elite? You just randomly unlock stuff for convenience, which is detached from each other, or you just don't. Having billions of credits or buying large expensive ships doesn't really mean you progress anywhere, because if Eagle is your favorite ship, you'll be sending most time in it.
And if the Eagle
isn't your favourite ship, you won't and would presumably like to acquire the credits to get another one. Sorry you were saying something about logic?
Progression isn't linear in the game for sure, which is the point (or one of the points) of a sandbox. 'Progression' is still ultimately something that every player will define for themselves as it's entirely dependent on what that player's personal gameplay preference happens to be, but surely you can see that if a player starts a new character, with zero credits, zero engineers unlocked and a starting Sidey as their only ship, then
whatever their personal goal may be, the game then provides a progression route towards it? And that simply playing through that route can be entertaining to some people, if not to you.
I've never 'randomly unlocked' anything in this game really, I've decided to achieve a particular task and set about it. The only things I've ever randomly acquired were the engineer unlocks when they were first introduced and there's no way I could have known that (for example) the fact I took a trip out past the Eagle nebula about a year before Palin was in the game as an engineer meant that when he appeared I'd already achieved his 5,000LY unlock requirement.
In general, do you play a game through once and then that's it, you never go back to it? If so I can get why you'd have a problem seeing how a new start could be entertaining for someone who already did that once (and there's nothing wrong with that at all, how entertaining each of us finds
any game is a completely subjective judgement).
If you're the kind of person who might play an RPG through three times using completely different characters just because it offers a different progression and gameplay experience despite ultimately following the same story, or might play through a squad-based strategy game several times just because you like to experiment with different tactics and leveling through tech trees in a different order or priority (looking at you X-COM series

) I'm surprised that you'd have trouble seeing how starting over in this game and perhaps employing some limitations on your playstyle, or following a particular (I'm so sorry for using this phrase) personal narrative could be appealing.