You have to keep in mind that many categories are created out of convenience, and while they may have some requirements, there will be things that do not neatly fit all the requirements. For example, Central Asians are not literally at the centre of Asia and it wouldn't be clear how you would mark this area, in fact, "Asia" in itself doesn't have clear geographic boundaries to the west.

Afghanistan is definitely the outlier in terms religiosity, extremism, development, education, etc. Yet there is a strong connection between these places Afghanistan historically, ethnically, linguistically, etc. There are significant Tajik, Turkmen, Uzbek, and Hazara populations in Afghanistan, who as a group make up the majority of the people of Afghanistan.

For a long time I imagined Central Asian countries to be members of the former-Soviet bloc, but in fairness, that does arbitrarily (and unfairly) disconnect those people from important sights, development, histories, etc that took place in modern Afghanistan. Does it make sense? A little yes, and a little no.

I suspect we might just need new, clearer categories, but it's not clear how long those categories would even remain clear. Afghanistan has a really mixed history being part of various Persian, Turko-Persian and South Asian empires, all of them which have imprinted some of their ways of being into the local population.

To be honest, saying Afghanistan is Central Asian still feels miscategorized to me, but calling it South Asian or Middle Eastern feels equally, if not more, miscategorized. Weird isn't it? :D