In my experience the people that change their MAIN ENTIRELY is a pretty significant amount and it's VERY usual at the start of new expansions especially among players that take gameplay pretty seriously but also if they want a new flavor. So for those people I think the current account -wide situation is pretty lame because they don't even know the flight paths on their new main or they don't even have reps or if they want to jump in a raiding tier subsystem like the essences of BfA it's (in part) like starting all over again so I really believe the game could embrace account-bound more but also to keep it fair it should have limits that are only character-bound (for example "sure you can get new essences immediately on your new main but your old main is losing their essences entirely forever!").