Answer:
because it bothers the ones doing work.
Step-by-step explanation:
the reason people do not talk while other are working is because you can affect their workflow by being too loud or making a lot of noise. doing this can in fact affect other people/students grade in the future. while speaking is the most effective way of communicating, there are boundaries and limits when it comes to being in a public place for the sake of others. talking should be kept to a minimum in class and if possible have a different place to do work or study so there are no unwanted interruptions.
hope it helps.