You will not get merit if you just "do bounty" and you don't really need it.
Beyond that, if you participate and contribute in discussions you will likely earn merit but if you try to earn merit you will likely not. Go to e.g. Bitcoin Discussion and read a few larger threads - you'll see what kinds of posts get or don't get merited.
In my observation it is easier to earn merits through creating or starting a thread that is helpful rather than participating discussions even if your ideas are on point. Not all users has given the chance to earn merits in just participating discussions unless the reply is clearly exerting some efforts to point out the discussions for the OP to absorb the information. However, most of my threads are just motivational and not really to earn merits but because of the users around that are also helping and promoting the welfare of the forum they consider some of my posts to be merited.
This is one of the good thing to happen in the forum. More users are helpful to motivate others to participate actively in discussions rather than joining bounties that could only resort to shitposting due to posts required to earn rewards in the bounty campaign being joined.
The rank and merit system is indeed effective in minimizing the shitposting activity resorting to other users become helpful lately to earn merits. I guess giving them 1 merit would be fine to continue their attitude on being helpful. However, rewarding merit is still a users decision to give if it is deserving or not.