I ever read theymos said you're allowed to have alt accounts with different characters, like if the main account is a nice and friendly user, you're allowed to being aggressive and become a public enemy in your alt account.
Of course, everything takes place, but the question is why: Why is this necessary? If a person has several personalities on the forum, this will, as the OP wrote, negatively affect his psyche. Split personality, talking to himself, everything suggests that offline such a person lacks attention, and he compensates for his "importance" on the forum.
I agree with you, OP; owning several alternative accounts is completely unnecessary. Those people who do not hide their alts enjoy the convenience; that is, it is convenient to own a separate account on a separate gadget.
In all other respects, this is the usual "milking" of the forum. Alternative accounts are created to increase their earnings. And we, in turn, see dozens of uninteresting posts, since it is quite difficult to manage several accounts. The forum does not position itself as a place of work, but many, either out of greed or poverty, forget about it.