Many halacha questions are straightforward. There is a Talmudic statement on the matter, and the Talmudic statement is codified in the various codes of Jewish law. When posting an answer to such a question, one can technically just post the Talmudic source, or one can post any of the sources where the law is codified.
But what happens if someone posts an answer with just the Talmudic source, or with just one code source? Well it is possible, perhaps even likely, that someone else will post an answer with another one of the sources.
Now let's imagine an extreme example. Suppose someone asks a simple question, like "what is the blessing for an apple?" One user reads the question and recalls the source where Rambam mentions the blessing for fruits of a tree, and he posts that as an answer. Another user remembers where the Shulchan Aruch codifies this law, and he posts that as an answer. Another user remembers the Talmudic source and posts that as an answer. Other users remember the ruling from other codes (e.g. Tur, Levush, Aruch Hashulchan, Kitzur Shulchan Aruch, a contemporary berachot book, etc.).
By the time everyone has posted their answers we may end up with 5-10 answers for a simple question. And none of the answers are disagreeing; they are just each presenting a different source for the ruling. (Yes, this may be somewhat exaggerative.)
My contention is that one comprehensive answer would be better than a bunch of non-comprehensive answers. Thus, a situation where we have a bunch of answers of this sort to a question like this, is not ideal.
Theoretically, someone can just post an additional answer combining all the existing answers. However, that doesn't seem like the best solution. First, it might look like one is simply taking advantage of content posted by others. Second, it won't change the fact that there are still a whole bunch of answers listed, and if the comprehensive answer is posted sufficiently after the other answers it is possible it won't even make it to the top position. Deleting the other answers seems wrong because it is other people's work that technically addressed the question.
To my mind, the best solution would be that the first person to answer would post a comprehensive answer, so that no one else would feel the need to post an additional answer (unless they were disagreeing). However, people are obviously not necessarily going to want to spend extra time and effort making a comprehensive answer, when a simple answer suffices.
Can we, and should we, encourage people to make their answers more comprehensive so that we can avoid having multiple answers to a question when multiple answers should not be necessary?
I have posted my suggestion in an answer. Feel free to disagree and/or post your own suggestions. Or feel free to disagree with the entire premise of this question.
This is not a critique of any specific user. I'm just noting something I've seen from time to time, and I think it can be made better.