Indeed a maximum number of pulls before a guaranteed Mythic would foster better player satisfaction, without breaking the economy.
So would a guaranteed unowned mythic from the Path to Glory/Power packs: it would result in more income for the developer, while limiting the purchases to once a month (so we still can’t just dump $$ and get all cards right away), and allowing those who wish to complete their collection via $$ to do so at a guaranteed pace.
The Devs’ Morality can be observed through their history of actions and inactions in this forum, and the potential clash with the above suggestions arises from the word ‘guaranteed’.
Self-Explanatory.
