There are enough merit sources and merits in circulation for a fair distribution of merit. More merits in circulation would mean more merits in the hands of merit abusers which isn't something we would want to see happening around, do we?
Not true, the merit abusers or spammers are not going to get merits at all as merit sources will never spam spam posts. So, it will be the good posters who will be rewarded if there are more merits in circulation.