$wgCentralAuthCreateOnView was dropped in rECAUb1908c5ada1e: Drop some backwards-compatibility code, during the AuthManager rewrite of CentralAuth which significantly changed how autocreation happens. You'd have to redo it from scratch.

Autocreation is somewhat problematic (T21161: Don't autologin if local account doesn't exist (don't autocreate if user doesn't explicitly login)) but then, non-autocreation would be problematic in its own ways. If we try to solve that, we'll have to do it in a more nuanced way, not just by forcing users to log in.

In T355442#9473266, @OriginalAuthority wrote:

Aside from the fact that some people just generally don't like it, Miraheze is at the point where Special:CentralAuth is taking a considerably long time to load due to the number of attached accounts. For some users, even if they haven't edited that wiki.

CentralAuth is a "use at your own risk" extension, fine-tuned to Wikimedia wikis' needs (which change, so the extension changes too, often in non-backwards-compatible ways). I hope at some point we can find the time to spin off most of its generic functionality (like global groups or global rename) so that they can work with any SSO extension that provides central IDs. But strictly for login / account creation, IMO you are better off finding something else and improving it to cover the use cases you need. Maybe WSOAuth.

That said if you really want to use CentralAuth and not do autocreation, you can probably do some magic with the autocreateaccount permission or with the PreAuthenticationProvider::testUserForCreation() callback, making sure it's only allowed on the login page or something like that.