My solution is very simple (altough probably difficult to implement), and I have already made a post about it at the BEGUINNING of this year (link bellow): Make the game smaller.
https://forums.warframe.com/topic/1337056-my-wishlist-for-warframe-2023-and-coming-years/
I know nobody likes "cutting content" but let's be honest, for a new player Warframe is like mount Everest. And those older players also think about it: how many times have you gone back to Earth or Mars to do (say) a interception mission? Unless it's a Relic opening mission or it's on Steel Path dailies, my guess is never. I know I haven't. New players HAVE TO play a tonne of missions to progress but veteran players (or WHEN they become veterans) end up playing a handfull of them... DE has the resources and the metrics to figure out what missions have more "player engagement" and what are necessary for progression. Yes, it would me a considerable task and it probably wouldn't be easy, but "throwing money at the problem" isn't going to fix it and for a FTP GAME(!) to ask it's players to PAY to skip "content" is worst than lazy, it is ridiculous.
BUT
If that is too much for DE, or the Community even, I offer an alternate solution: Have a roadmap where the player can see it's progress into the story/game (a book could work since we'll have it has a weapon soon), and have the player select what "chapter" he wants to work for. A bit like what happened with Login Rewards where the player can choose which reward to work for, have the possibility of the player follow the path he wants. I don't think ALL of Warframe arcs are linear so it could work has a solution to "skip" some content while retaining the main one towards DE intended goal. But this way, we leave the player to make that decision.