I’m not sure I understand your question fully; it’s hard to tell without knowing your site’s needs. But: ACF’s ability to conditionally show fields on different post templates, taxonomies, etc. does make it possible to avoid creating different post types when the default post types and conditionally-shown ACF fields will suffice.
Custom post types are certainly not obviated by this plugin, however. For example, a website for a running club would have custom post types for race and course in addition to the default post and page post types. An ACF object relationship field on the Race edit page could tie it to a specific course.
Does that make sense?
