I think it means there are more new zeta abilities being released than our ability to obtain them, leading to a growing gap in his collection (oooh I will never be able to collect all these zeta!)
While it's true zeta come at a trickle, I don't really mind not having enough of them to zeta say Pao or K2.
To the OP: just make sure you always have at least 20 zeta material in your stash. Only assign one when you are above 40. This way you'll always feel you have a reserve for that emergency case when you really need one, not just want one.
