Why are all the people who send text messages to Baidu asking questions anonymous?

Sending text messages Baidu knows that people who ask questions all display "Questioner: Know the mobile phone users". For the privacy of users, Baidu can't disclose the mobile phone number on Baidu.

The reward points given by questions are all given by Baidu, usually 20 to 40 points. You only need to pay 1 gross for each message, and receive it for free.