People who build "personal brands" on twitter should be condemned. It should not be recognised as a valid use case. There is a reason why people like dril came onto the platform to lampoon and confront the absurdity of brand twitter: that corporate twitter accounts obliviously chose to cohabit the same space that everyone else uses to discuss ass eating and gender politics, and that there's assuredly nothing more pathetic than being a "personal brand".
Journalists are the absolutely the most egregious examples of personal brand twitter. This use of twitter exemplifies the problem identified in this study.
You say that it shouldn't exist but don't elaborate in the assumptions of why. There are some major unspoken assumptions to their illegitimacy.
My best guess is the sheer tackiness of self-promotion involved? The control of corporate brands being antithetical and clashing to the "rawness" of talking about being hit on by old men before menarche and thus deeply phony and "uncool".
Are the objections moral (it is wrong even if it works), functional (it just doesn't work), or both (it is wrong and doesn't even work)?
Journalists are the absolutely the most egregious examples of personal brand twitter. This use of twitter exemplifies the problem identified in this study.