I noticed that if I vote down to a spam or invalid/ incorrect answer or question, even my score is reduced. Users reporting vote down are helping site from spam or incorrect or misguiding information.
What is logic behind it? Score should be reduced for the person whose question or answer is voted down
Anyone have idea why so?
First: For spam, you can cast a flag instead, there is a specific flag for 'spam - Exists only to promote a product or service'.
For downvotes, the user being downvoted gets -2 reps, the person voting down gets -1. If the answer / post is then deleted, all reputation is given back.
The reasoning behind the person voting down losing a point is somewhat given for example here. This is designed to make people think twice before downvoting, to not just do it on reflex or as a "revenge".
Also, from here:
The motivation behind it is to put emphasis on up-voting or not voting at all. This way, down votes will carry more weight and it will also prevent users from abusing the system by down-voting excessively.
According to what Jeff/Joel discussed on the SO podcast, they wanted to find a way to discourage users from down-voting for less legitimate reasons (say a pro-Java developer down-voting everything remotely related to .NET or the like).
