The spirit of your post is correct, but the details are slightly off. No one complained about CORES until Forsaken. Complaints about the MILESTONE system actually started with Warmind. Bungie began their effort to THROTTLE progression with Warmind....and people started to complain then. But the complaints were mild because people were also looking for reasons to play. So they largely tolerated the changes. The real push back came---as you mentioned---with Forsaken. That's when Bungie REALLY moved to smother progression....and to break the relation of progression to player time-investment by dramatically raising the cost of infusion, adding cores as part of that cost..... ....and intentionally undersupplying the game with cores.