There are three main reasons for stopping selling platform tickets:
One is that there are many people and luggage in the station, and there is no screen door on the platform, so the sale is stopped to ensure the safety of passengers on the platform.
The second is that platform tickets can't be registered with real names, and they are stopped to prevent evasion.
Third, the suspension of sales can effectively curb the theft and kidnapping of people with ulterior motives in the waiting room with platform tickets.