I agree that Google doesn't have a magical EAT algo that if it sees a "Dr." before the author's name it automatically jumps to the top of the rankings. That doesn't mean EAT isn't impacting the rankings.
For example if you are providing content on a medical topic and you hire a high school student to write the article, it is probably not going to succeed. That writer will probably not give good information and/or mention all the pertinent details. Bad content leads to weaker on-page signals plus weaker user metrics which also scares away backlinks. If you had a good writer that is well informed like a medical doctor cover that topic aka using an EAT mindset you end up with good content which have good keyword mentions, relevant title tags, engages the users, and attracts social & backlink love. Of course you can go overboard and use an overqualified expert who won't connect with your profit generating audience because they are talking over their heads. I personally think you need to seek out that sweet spot in the middle where you connect EAT with what the profit generating audience wants and that is not an easy to manage.