As far as I can see, system of merits here is some sort of reputation.
Indeed besides it is one of the variable that you need to rank up as well, this is for personal perspective by the way.
distinguish experts in cryptography from inexperienced users
Wrong. You do not have to be experts in cryptography.
since we know how much we can trust a certain user.
Merit and trusts are different. To get merit you will not need to be a highly trusted member. Look at my trust. 2 negatives but still I receive merit.
merits can serve as a moral encouragement for the help given to others.
I can not speak for others but when I send merit I keep my mind empty. If I spot a good post then I merit it when I have sMerit available.
these merits don't mean anything and can not be used at all.
It's a feature of this forum not a cryptocurrency or anything else that will have a value outside LOL
So, why do so many users try to get them from the very beginning of their registration, as if this is their main goal on the forum? It seemed to me that merits should be just a tool, not an ultimate purpose.
You already have the answer now.
Numerous daily posts like "How to get merits", thousands of similar responses to posts only worsen the state of the community and do not do any good, but kill communication, don't they? Or, maybe, I've missed something?
You missed that you and the other guys who are talking about "How to get merits" and stuffs are no different at all.

Just read it here...
....I encourage people to give merit to posts that are objectively high-quality, not just posts that you agree with.
I need merits so that I can have sex with my alts, also I can use them to bribe theymos. How can you not know that?

You gonna end up having HIV positive soon

... as long as they are a constructive member of the forum, and aren't spamming their way through the ranks.
Absolutely!