I respectfully disagree. If merit sources had too many posts to pick from and less merit they'd be more pressure on them to focus on actually good posts by good members so they can reward their efforts by making them rank up.
I'll speak for myself. If I had less sMerits, I'd simply do what I had been doing before I become a merit source; merit the same posts, but with less merits. I don't feel like I have more pressure on meriting "good posts" now that I'm merit source. Whenever I find an interesting post, I simply merit it. That's all, and I'd say I'm biased to an extent to newbie posts, because I want to encourage them continue their journey and rank up.
I'm quite certain many people have the same approach now, but things work differently on a macro and on a micro level.
The macro level is that if everyone has less sMerits and there were far fewer merit sources, the result of having less merit to go around would be that the responsibility on spotting and rewarding good posts increases.
I certainly wouldn't rather to help a user who sees the forum as a milking cow instead of an Internet board, rank up. Why am I the one to blame and not them for being incapable to produce somewhat medium quality content?
Precisely because there's a lack of new users with good posts I believe that we don't need new merit sources. At this point in my opinion new merit sources should only happen if less active ones are removed and their sMerits rescinded. When forum activity from new users goes down merit sources should ideally decrease, not increase.