There is also a backwards compatibility thing. There are times that some might have used get_option() instead of get_field(). If ACF wipes the options table then the update could break a site that does. For anyone that’s done this, or has a site that may have been built by someone else, I would most definitely back up the database before deleting data. You may need to go into the template code and find those places using get_option() and switch them to either get_field() or get_term_meta()
Yes, I’ve done this, why? So that sites keep working even if I need to disable ACF for some reason. I have a couple of sites that need some work 😛
