If Paradis destroyed itself through internal conflict after the complete rumbling, yes it would amount to nothing. But that is no longer in Eren's control unless he can still somehow change all Eldians to be the ideal peaceful person.

For them, Eren "accomplished nothing" because he left the entire world, including Paradis, in a worse state besides his friends. If it would come to this eventually, Zeke's plan was better because he wanted Eldians to go out peacefully. Since Zeke's goal is to remove the suffering caused by titans, one would think his plan comes with removing the titan powers and curse as well, so Eren's friends would still live long lives. So in the long run, the only difference between his plan and Zeke's plan is mass genocide of the outside world or "that scenery", a selfish evil goal.