It is quite common for websites to change their request-handling logic as well as their displayed data regularly. If a program that makes requests to a website has considerably inflexible logic to interact with the server of the website (for example, structuring its requests in a specific format, only handling one kind of response), then if and when the website alters the way it handles its client requests, the program will most likely stop functioning correctly. This situation happens frequently with web scraping programs that look for data in specific HTML tags; when the HTML tags are changed, these programs will fail to find their data.

This practice is implemented to prevent automated data collecting programs from functioning. The only way to keep using a website that recently changed its request-handling logic is to analyze the updated protocols and alter our programs accordingly.