I haven't looked into it deeply yet, but I am wondering if it is possible to dedicate several computational power of different computer/servers for one instance of Minecraft. There are limitation of CPU core counts and RAM size on a single machine. How do popular Minecraft server network service provider such as Hypixels solve this issue? Any insights?
Hypixel uses a software similar to BungeeCord, which allows multiple servers to run under one name and sharing some files, and for you to be transferred between the servers. This is used as the hub system in almost all servers today. However, if you have one world, you cannot shard the server.