Your claim <This is why I support the 实名制, let people know your identity.>
I think that there are purposes behind why people do not use real names in forum regardless of whether what purpose they serve in a forum, both negative and positive.
Firstly, lets say for example, a person who speaks the truth for the sake for improvement for all. We must understand that everyone have different views and opinions about a certain claim. Some are opened minded, some are closed minded and these are the people who are not willing to take in facts and ideas and whats worse is that these are the people who may get into violence and things. Who knows what they will do to the guy outside?
So even if someone is here for the right purpose, it would be still safer for the forumer to remain identity hidden.
If you were to notice, usually those who has their identity known do not really say much in this forum. I think maybe they are also worried about whatever may happen to them if someone else who just can't understand their logic and reason no matter how well and reasonable they express their views out. It can be rather dangerous to have someone who hate you and aims to do something to you in the dark. Right?
So in conclusion, i think that it is to protect people. but of course there are people who take advantage of it and say nonsense out there. But i also believe it is possible for ip check.