Content island: the game. Warframe features dozens of progression systems, each of which is hundreds of hours deep, and very few of these systems interact with each other in any way. Once you've built out a good warframe and weapon setup, you're basically as strong as you will ever be. Grinding out railjack, or the open world areas, or focus does little to nothing to increase your character's power. Hitting that power limit drastically reduced my interest in continuing down Warframe's thousands of hours of grinding.

if you're interested in grinding to make a number go up, Warframe will likely hold your attention for a long time. If you're looking for deeper progression I think Warframe is still worth playing, but be prepared to put the game down when the grind becomes unrewarding.