1. These missions can consume a lot of time, at 20+ minutes per game and a requirement to hit round 20 every time to get credit.
2. These missions are among the least interesting, as they don't promote exploring the game in the same way the other missions do.
3. These missions serve as blocks to the other missions, penalizing those who don't have time to play that many games by denying them other reward opportunities. This makes the TFT beta awards achievable for those who don't have the time to play 30+ games a week (or want to play some normal *League* as well).