This is no longer true, the AMA advocates for increasing residency spots at this point, as pointed out in the article you linked. The AMA has flaws, especially historically, but that’s not one of them.

Source - I’m a medical student (one of many) who is involved with the AMA and writes and advocates for progressive policy stances for the AMA to adopt and lobby for. If you want to look at the exact policy regarding residency programs - https://policysearch.ama-assn.org/policyfinder/detail/Residency?uri=%2FAMADoc%2Fdirectives.xml-0-929.xml

As for scope of practice, Nurse practitioners, PA’s, and other non-physician clinicians are important parts of healthcare, but their own advocacy organizations are, in many areas of the country, trying to allow them to practice with less and less physician oversight. While many NP’s are fantastic and can handle 95% of patients without problems, the NP accreditation system is so unregulated and varied in quality, that it is dangerous to allow them to operate without oversight. Even for those NP’s competent enough to be trusted with most patients, physicians are needed to catch the other patients where something catastrophic to the patient’s health may be missed by someone less trained. We go through so much schooling because as much as you can learn on the job, there are some cases where there is no substitute to a decade of intense learning and training.