Question: why theres a blacklist cap..?

[Haibel]

The information in this linked post from Reddit would suggest that the BL and FL are both server side data;
http://www.reddit.com/r/ffxiv/commen...tafriendslist/

He's right and he's wrong. He's is correct that character relationship is done by Character ID. Certain Data when you move the game to a different machine will download from the server.
Your character Data folder on any machine you log into will have the same name. The stuff that gets download are mostly flags to let your client know what jobs you have and what actions you can have open. To my knowledge, there are only two files that get download. It's been awhile since I've added a new machine that I play on. FFXIV_CHR_01.dat and ACQ.dat all others are created client side.

Stuff that doesn't move machines. Settings, Gear List, Macros, UI Changes, Keybinds Etc. Stuff That moves machines and Download every time you log in. Character List Tied to the account and the current gear equipped to these characters.