I think there's likely some truth to this theory, but it's hard to get a real sense for the scale. If VFTW's "monetary inflation" analysis is accurate (and it makes logical sense to me), then a group of people accumulating and redeeming huge stashes of miles is going to cause problems.
However, I don't have a good sense of whether we're talking about 1% of people causing a disproportionately high 10% of the "damage" due to playing the CC, MS, etc. game really hard vs. say a somewhat broader 10% of people doing a somewhat less disproportionately high (on a relative basis) 30-40% of the "damage". Whatever the number is, you can probably blame "those CC-whoring bloggers" for a reasonable chunk, but FT, Bank's advertising budgets, and even mainstream news coverage likely contribute in a pretty meaningful way.
It's really hard to estimate scale when we're talking about numbers this big, and I imagine all of us here have a pretty tilted view. I work in consulting, and while most everyone is mindful of points and miles and status and all that, I can't think of a single other person in my group of just under 100 that is anywhere near the level of crazy that I have (and I pale in comparison to many who I think are TRULY crazy
). I'd say no more than 5 who are even 1/4 my level of crazy. No one is manufacturing spend, and only a small handful are churning cards (and their definition of "churning" is probably 3 cards a year). These are the anecdotes that lead me to believe that the game still just isn't that pervasive, but again, they're only anecdotes.