Well, depends on how you look at it.
One of the reasons we have been given for the content vault is the fact that having to manage all content from every DLC, season, etc. every time they add something is pretty ridiculous. And let's be real, it is.
Now the obvious counterpoint to that is "Actual MMOs add endlessly all the time!"
And while that's true, there's a big monetary difference.
Destiny 2 made $300 million in 2019. Final Fantasy: A Realm Reborn made over $600 million from July to September in 2019.
An actual MMO [i]more than doubled Destiny 2's annual revenue in 3 months[/i]. And that game died on release as the original FFXIV.
Now does Bungie likely have a lot of money? Sure. But does it make sense form a business standpoint to constantly have to work on old content more and more as the game grows if the company isn't? No. Not really.
What Bungie needs to do is define themselves as an MMO and stick to it. They need to guarantee top tier content. No more "walls of text" for story. Let us see it. Guaranteed 2-3 raids and dungeons a year. Guarantee 3-4 sandbox updates a year. Guarantee several new PvP maps a year. Guarenter less reskins and more original weapons and armor. The list goes on. The moment they do this, I can promise you people will pay a monthly subscription and the company will grow tremendously.
But it seems like Bungie is hesitant to do that, as they should be, so they're skirting around it with the DCV.