Eugene It's not a limit from them how long we play,... Of course if you handle it, like who is playing for rewards mainly, or only, you think that badly. The game is mainly for fun, not about rewards only. I suggested here few things to be better the things about it for most of players, check it:
https://forum.partyanimals.com/d/2789-few-things-about-the-level-100-mystery-box-limit
And i wrote there plus experience comment with an extra suggestion there not long ago in a new comment. I hope the developers will take it seriously and i hope they will change it for better!