Player engagement as measured by how much they play and for how long is as valid a metric as any after sales.
If you don't care for the repetition, gating and the RNG of the reward system, go play something else. Games are designed for specific audiences and this design seems to be working out for them based on their own words.
Arguably, more engagement = better game. Just because you don't care for it styil, doesn't mean it's not successful. You hate nearly everything in the game anyway as evidenced by your many threads so why torture yourself about it.