I think this is one of those issues that Disney enforces when they want to, not on a regular basis. I used to eat 2-3 times per week at CR, over a period of several years. Most days having an ADR was a quick wave through, with no limit on parking time. Sometimes I was given a three hour pass that had to be displayed on the dash of the car that said the car could be (could, not would) be towed after that time expired. One time, just once, I was turned away at the guard gate even with a valid ADR, and told I would have to park in MK parking and monorail to the resort. So even at the same resort my experiences varied widely, depending on how busy the hotel and MK happened to be that day. Yet during this time, the official policy was always parking allowed only while dining or shopping, not all day. I am glad you had a positive experience but I would not count on having that experience all the time, especially as they tighten down on parking at the resorts.
Disney is well known for not communicating official policy well to the CMs who work there. Most of the time they will just tell you what they think you want to hear to avoid a conflict. So there is often a gap between actual policy and what is told to individual guests. I do not doubt you are being truthful about what you were told. It just doesn’t line up with official policy as written by Disney. Unfortunately that is par for the course with new or controversial policies at Disney.
Back to the topic at hand . . .could a part of the new CM at the guard gate be related to more people trying to park at resorts free since the theme park parking fee went up a couple weeks ago? I can’t believe it’s just a coincidence. I would guess there was a significant uptick in the number of cars hanging out all day that weren’t on the registered guest list and they want to nip it in the bud.