If rep was account wide, I wouldn’t have to regain Dreamweavers rep from Legion, on 2-3 different alts for legendary artifact skin, some other stuff or dungeon pre-requisites.
There was something on my Blood Elf paladin I needed and there is something I still need on my Night Elf Druid and I just don’t even bother to grind that rep again.
I’ve done legion with 2 classes now and i’ve had to gain a lot of rep with various factions, including the nightborn, which I still have to do, again, on my druid just for the vendor rewards.
Now if I was ever going to be able to play a Void Elf Shaman, i’d have to do it all over again, not just once to unlock void elves, but again as a void elf.
That’s just in Legion.
Then there’s the fishing rewards, reputations, legendary, that I would be required to do, on any alt I want to fish on without feeling gimped.
Then, there’s all the recipes, locked behind reputation vendors.
One Main can’t use all the profession-craft recipes or gear, I can’t even buy the armor to send to alts for transmogs and even trying to collect the transmog on a plate user, no cloth/leather/mail gets saved unless its the primary armor type used, on a paladin, that is plate.
So that goes to another point, about having to run dungeons, on multiple different alts, on multiple different specs per those alts, just to get/drop/find/save transmogs.
Then, to do some of those dungeons, some require items, which are, again, locked behind reputation vendors, Stormheim being a notorious one wanting exalted for a valkyr doodad to do a quest for a quest chain that isn’t account wide once completed.
So boop.
And THEEEEEEEEEEEEEEEN
I can’t tank as a Shaman but I have earth shields. Ok bye.