Adding action to a Webhook provides compatibility with other plug-ins.

This is because LINE can only set up one Webhook (this is normal).
Therefore, when a website wants to use several different plug-ins related to LINE, it can only choose one of them due to the Webhook problem.
Therefore, it is recommended that when you receive a Webhook, after receiving the request, and after verifying and reading the relevant data, you set up a do_action hook with the destination/events you have obtained, so that other plug-ins can work together more easily.