Is it possible that the rating system is eventually prone to inflation from non-active users?

Oh no, is there an inflation in Chess.com?!

Damn, I was thinking about buying premium membership...

It works both ways - when you play an underrated player, whether he started out underrated or is just rapidly improving (as many young players do), you suffer deflation, as does everyone who plays him until his rating matches his strength.  This applies no matter what the results of individual games:  those who beat or draw him win less than they should, so they still suffer the deflationary effect.

The tendency is for these effects to nearly cancel each other, so the pool is only slightly affected.  I presume the administrators and/or statisticians are monitoring the pool for net loss or gain of points beyond normal fluctuation, and would take steps to correct it should the system get too far out of whack in either direction.

cool

What a waste of a thread resurrection!