But I disagree with the gatekeeping argument. Why should only a few decide which content is good and which is "not worthy enough". Why not giving out a portion of Merit to every account older than 3-6 months and let the masses decide?
Because most of the masses are spamming nuisances, and they are the reason the merit system was introduced.
The "few" who decide which content is good, are the ones that the community has decided are merit worthy, and that isn't just the "high ranking".