Merit sources are just members who've (sometimes) volunteered to be distributors of merit, and they have no obligation to keep any sections un-ignored if they so choose.
Of course, there is no obligation on your part to visit certain parts of the forum, but I have always thought that it is bad to ignore, in my opinion, very important parts of the forum, such as the Bitcoin Discussion board. Regardless of your belief that there is too much garbage and spam, I regularly read, post and report anything I think is bad or against forum rules. It may not mean much, but it makes more sense to me than the option to ignore the whole board.
I assume that's what you meant in your above statement, though it wasn't entirely clear what "being influenced in this way" was referring to.
If someone opens 30 threads in 30 days, and they are all supposedly very high quality, how is it possible to get only 17 merits - does this mean that most merit sources have that board on ignore? I just want to say that it would be more natural for merits sources to find posts worth merits, than to draw their attention to them in this way. Although I understand that people value their time more than anything else.