You had to be there for the first time people stepped into the Vault of Glass. You had to be there for D1's Outbreak Prime quest. You had to be there for Laser Tag Weekend, when Whisper was discovered, Niobe Labs, or for Wish Ender month. Removing activities after a certain period of time doesn't add anything to the experience. There are people completing The Whisper for the first time in S9, and it's just as much of an experience for them as it was for people like me who completed it when it came out. Trying to artificially create moments like this turns the game from "you had to be there" to "you [i]have[/i] to be [i]here[/i]." You have to be here to grind out god rolls on the new Sundial weapons before the activity goes away. You have to grind out 100 levels on the season pass before it goes away. You have to run through CoT to get all 19 lore pieces and the emblem because it goes away in 2 weeks. Sure, you don't actually [i]have[/i] to do any of these things, you could just decide not to care, but for people who do care, it just adds a stressful sense of urgency.