As the title says, when you host a server, you or your friends has to wait 30 or more minutes for the host to add all the mods they want to add, then check the mods for duplicates, for example "Exhaustion boost fitness" has a reduced version, and it causes problems if they are both active, so being able to make a mod pack before hand would be really nice so you create the server settings you can just select the mod pack and bam, your loading up easily.