It all depends on how the chat system works. We all don't know that for sure since the game was made over 10 years ago. We are not assuming things. We are just discussing on how the game works. If I remember correctly the game can run off multiple network infrastructures like the chat system can run off 1 network structure while the game runs off on their own server. If I also remember correctly if you zone in or out to areas, the chat system stops. This means it can indicate the chat system runs off a separate server or a network of its own. It is all guesses. I did remember one of the Dev people stated they will be able to make adjustments to LS capacity limits easily since it does not harm the game. If I remember correctly they made an annoucement about adjusting the LS structure in the future.
I know today MMO's do not have this issue anymore due to breakthrough technology. FF14 has a Linkshell system and now a Company System (Still need to study about this.)
If you guys read on the FFXI reddit forums we got a reply stating they are in process of discussing LS changes and such. Its progress for now and we have to live with this issue until they fully announce it. I have good feeling they will make the linkshell easier. We all know SE today, they focus on content more and keeping the game alive. So we just have to sit back and relax for now until they make that announcement.