Because long term growth is the ultimate the goal of the industry, the bulk of what we see in comics is done to serve it, and in Meltzer's case it worked extremely well. If you achieve that everything else is irrelevant.
Is all that growth due to Meltzer, or to writers like Snyder or Bendis or Johns who have stayed on books long-term and became architects of what went on in Marvel and DC?
As for Justice League...
15 JLA 125 $2.50 (last JLA issue) DC 74,313
2 Justice League of America 12 (Meltzier's last issue) $3.50 DC 131,412
A year later
12 Justice League of America 24 $2.99 DC 81,408
two years later
29 Justice League of America 36 $2.99 DC 57,488
So much for long term growth...