A couple of weeks ago I planned to rerun low level zones on Cata via my alts, for achievements, so I can have then on my account.
But a quick check told me account-wide achievements don’t come with Cata, they come with MOP. Is that true?
I do have some memories thought that mounts were somehow shared. How did it work?
On the Beta, achievements are indeed account-wide. And it wasnt, indeed, added until MoP - but neither was account-wide mounts/pets (and those are currently present in Wrath Classic). Heirloom tab wasn’t added until Legion, yet we have it in Wrath Classic.
I hope they’ll add for Cata.
Account-wide pets and mounts are already available? I have to check it, OMG. This is what happens when I’m sticking to a single main since 2019 
Not sure when it was added - I took a break some time during Ulduar, and when I returned it was there. I do believe it was released with ICC, though.
I hope we get account wide achievements for cata.
I decided to check it- and you’re right. Mounts and pets are account-wide. Achievements, however, aren’t - unless they’re tied to a mount.
When Classic was released in 2019, the client was based on Legion, so it’s not surprising you see the basic technology of Legion there. But the features that didn’t exist earlier weren’t added for Classic.
Will they add account-wide achievements for Cata Classic? In the spirit of True Classic, it doesn’t - they didn’t exist until 2012, until MOP.
On the other side, a lot of achievements in Classic are tied to the revamp of the Old World, so if I don’t redo then on main character on max level, I won’t have them added… and it’s silly to redo them on main character. So yes, make them account wide so doing low level alts is worth it!
I think I’m in a minority on this matter, but I really don’t like account-wide stuff. The achievements and the items I get reflects what I’ve done on with my character. They belong to the character, and it is something that gives the character additional value.
Stuff like account-wide achievements makes it feel as though I am playing an account. The individual journeys of my characters become less unique. It’s one of those things that kills the sense of being immersed in a virtual world. Perhaps it is an exaggeration, but characters are no longer individuals; they are all just representatives of the player’s account.
So I am sad to see it added, just as I was sad to see them add account-wide mounts and pets in Phase 4 (where were the #nochanges-screeching crowd then?). But it’s not something I’m going to quit the game over. At least not yet.