Hi Lenarius,
Great question! We store these talent loadouts on the server so that you have access to them on any device you log in on. However, because we’re persisting this data, this is one of the many parts of the game service where we need to be mindful of storage requirements. It may not feel like a lot, but all of the saved talent builds across all the characters in WoW really adds up, so we have to be intentional about even small additions to the memory footprint of a character. Fortunately, for players who want to save more information than we allow server-side, there are addons that let you save and manage many more loadouts locally to a device.