I'd argue the difference is how the complex ecosystems handled parasites.
On the one hand, Blizzard enabled balance-breaking monetization, and TF2 enabled costume-breaking monetization. Blizzard could've made just as much (or a lot more really) money just by enabling cosmetic rewards instead of gameplay rewards.
I feel like I quote this once a week [0] but Cory Doctorow makes a ton of great points on this and related subjects in the linked essay.
On the one hand, Blizzard enabled balance-breaking monetization, and TF2 enabled costume-breaking monetization. Blizzard could've made just as much (or a lot more really) money just by enabling cosmetic rewards instead of gameplay rewards.
I feel like I quote this once a week [0] but Cory Doctorow makes a ton of great points on this and related subjects in the linked essay.
[0]http://craphound.com/complexecosystems.txt