I’m not a huge Starwars nerd, but I am perfectly willing to accept that someone more naturally in tune with the force (as I understand the concept of it) would require significantly less training to tap into it.
What’s so hard to believe about using the jedi mind trick without training? It seems more likely to me to do that intuitively than to successfully parry a charge. As you even bring up, Yoda was insistent that Luke be fully trained to face Vader, but was it his physical skills, or his mental readiness that he needed to be ready?
Also, I agree that in the last movie, not only did Rey seem to shortcut all the training and preparation that the earlier stuff seemed to make requisite, but she also seemed too devoid of personal flaws. Fans like character flaws. It makes them more sympathetic. Tom Cruise built a career on flawed characters finding redemption. heh.
I was a Trekkie before they became Trekkers.
Mary Sue was invented by a female Trekkie in fan fiction in the early Seventies. She was already jaded by all the teenage prodigies (see later Wesley Crusher in STNG) cropping up in mediocre fanzines. James Kirk was truly a prodigy, but he had earned his success: He was “a walking stack of books” in the STOS - before J. J. Abrams rebooted ST and made him a Marty Stu who could drop out of the Academy and be an all-around jackass, and yet still end up beating everybody older and more experienced at the game. Pathetic!
To make comparison:
Though her character was certainly used for SJW propaganda, Carol Danvers as Captain Marvel was emphatically not a Mary Sue (as many journalists who do not understand the derivation of the term asserted). She was an experienced adult, with extensive training in both the Terran USAF and Kree Strike Force, and one imbued with Kree powers from the explosion.
In contrast, Rey is emphatically a Mary Sue: an adolescent with some random experience and expertise, but not nearly enough to account for her almost instantaneous mastery of both foreign technology and the mysterious Force.
Her Hero’s Journey took no time and effort at all: She arrived full grown, in effect. It makes the entire saga feel phony and boring. She did not earn it.