When running an older version server like 1.12.2 and wanting to upgrade to a newer version without having to make backups of your files and fear losing data
If the client is freezing or crashing due to a memory error, it is most likely because your client does not have enough RAM allocated to run correctly.
Server crashes can occur if you do not have enough resources to run your server or installed a non-functioning/incompatible mod or plugin.
Datapacks provide the player a method of further customizing their Minecraft experience on a vanilla server without having to upload any mods or plugins.
Scheduled tasks allow you to automate your server managing process by either making a task for it to start, stop, restart, update, or even execute commands, etc