I have no any problem of catch up, back in Feb 2017 when I'm fresh in Nutaku side.
I use only about nearly 2 months to boost myself from zero to 400k TP.
From that day until now, I didn't see any change much in the game.

Event that player can easy complete.
Story mode that player can play when they have free time.
Re-issue that player can skip.
This game don't have any real competitive content, player can freely develop themself as they want.

I do agree with A Time to Screw, about old player retention.
I have 22 ally left since my last login during X-mas.
Less than 10 still login in this past week, other gone for at least 3 months.
Severals ally gone for 280+ days.