Ah- ok. I honestly don't think they were saying it's discrimination along the lines of "we're not going to offer you a position because of where you are from", but more along the lines of places looking to fill positions quickly getting applicants locally for practical reasons, rather than discriminating against non-locals. With all participating agencies and applicants in the country agreeing using APPIC as a centralized place for lists of internships as well as universal applications, it basically becomes and process with a nationwide scope. APA could certainly continue to mandate this process, but the universal notification day and rank listing hold it all together. Without the ranking lists and match day, you'd likely have a situation where top applicants would get multiple offers, holding out for the best ones, while other applicants (many of whom were also very qualified for the positions) would not get offers- at least until the top applicants had all made their decisions. The end result would be many more applicants not getting a position, and many more sites not filling their positions. From the site's perspective, doing all that work and not getting filling positions makes it a hard sell to continue to fund those positions. From the applicant's perspective, many more degrees are held hostage by factors outside of the control of the student or the degree granting institution. Long story short, if it's going to be a truly nationwide process overseen by a third party (e.g., APA or APPIC) the absence of match day and rank listings would make it much to cumbersome and unwieldy to be managed by the internship sites, and thus more difficult for applicants to match somewhere. As an applicant, a lot would come down to your negotiating and bargaining abilities.
It's hard to come up with a better plan. I do think that anything related to earning the degree should be under the control of the degree granting program. Complete your coursework, thesis/dissertation, and university affiliated clinical training and practicum work, you get your degree. I do struggle at what to do about non-university affiliated supervised fieldwork required for licensure. My instinct is to put that on the student, assisted by networks and contacts of the graduate program and mentor. However, I don't think that would lead to enough students getting good fieldwork training, particularly in more rural areas (and it would create extreme competition in more urban areas).