Doudian refers to the e-commerce platform on Douyin. The reasons for limiting users to only one account may be as follows:

1. Avoid fraud and abuse: Limiting each user to only one account can reduce the risk of fraud and abuse. If users can bind multiple accounts, it may lead to problems such as false transactions and malicious comments.

2. Simplify operation and management: Limiting one account can simplify user operation and management and avoid confusion. By binding one account, users can more easily process orders, manage stores and communicate with buyers.

3. Maintain reputation and reliability: Limiting one account can help maintain the reputation of users and the reliability of the platform. If users can bind multiple accounts, they may have a bad reputation and affect the overall trust of the platform.

The above is just one of the possible reasons. The specific reason for limiting binding to one account may also be affected by the platform's policies and regulations. In order to get an accurate answer, it is recommended to consult the official support of the Doudian platform or refer to the relevant instructions and documents.

If you have further questions about Doudian or other related issues, please feel free to ask questions. I will do my best to help you.