Big difference in WoW and most other MMOs is characters can only be 1 class. You pick your class when making the character and they are stuck with it for life. You want to play a different class you made an alt, which came with its own set of raid lockouts. Now in FFXIV your alts are all on the same character which only has 1 set of raid lockouts to use.

The thing is leveling other jobs on the same character is a lot easier then doing it on separate characters due to only having to do 1 set of missions and quests to unlock everything. In games like WoW you had to do all those quests and stuff over for your alt to level it. It takes around 3 weeks to 1 month to cap a character in WoW vs like 2-3 days in FFXIV.