Well, to be fair, there are some exceptions... BLM is an easy one, but there are others. Managing hate in a non-abyssea area can be important at times--something generally learned as you are grinding the levels outside abyssea and book burning alliances. Then there's the issue of timing abilites and support spells too--things are a bit skewed in Abyssea when you have the masssive stats and what-not. Subtle nuances in most cases, but it can be an issue if you aren't accustomed to having to balance something like MP cost against recovery in a long fight.