i know they do, i just thought "oh a different character, wait hmmm any character can become any class :/, this doesnt seem right", think of it as a job (as it is one basically). you are elder and you have "said job", you dont go and suddenly work somewhere else if you need it, say you wanted some fags from corner store, you dont get a job there and make them, you just buy them from another person. so sticking to one class for one character seems well fit. i mean you can still change class but just by using a profile.
Also another thing that made me think this way was. Say i am a cultivator will char named bob. Bob up's his cultivator skill to get more better and frequent oranges from his plant, but wait bob wants some ammo *sleeps* becomes engineer *wakes* makes it and walla ammo and reverts. he also wants ammo cheaper so he misses out on upgrading cultivaor again and does engineer for when he changes (he is now not just a cultivator so why does he need to change profiles ever... *pfft* no need). But if you cant change class as same character it involves more effort to get what you want so you will be more likely to RolePlay and go to someone who can make the ammo. This also means that you can seperate skills by character, so if i have scavenger skill i can upgrade him solely on scavenging.
Anyways, its not my choice but i hope you see my point in same way i do.