Destiny doesn't have enough content with everything we have to afford timegated content either. They completely made the other two raids pointless to do unless you wanna get motes of light or you need to do this recent timegated quest to kill Atheon. They wiped pretty much all the end game content before TTK to being pointless to do, where TTK should've just added to the endgame stuff to do. This timegate is to unnaturally keep Destiny alive because if we had everything like in vanilla release we would forsure have left Destiny behind already. The difference here is TTK has just as much as Vanilla Destiny but there are items we can't get until the Time Gate is lifted for said items. This means you pretty much already done everything TTK has offered expect get all the weapons and armor in TTK. Also this is designed to keep us here until Destiny 2 release of next year.