I’d be willing to bet that your interpretation of its performance is flawless, but if you put a a thermometer in the vents it would be substandard performance. The whole is my AC working right thing is not an across the board even consensus, some people don’t like it as cold as others simply put. I put a thermometer in my wife’s Lexus and my sons Tacoma and both of them will blow low 40’s at idle in 95-100 deg temps. My Rams AC blows 15-20 degrees warmer than my other two vehicles. Only with the valve in place can I get similar temps. Some people are fine with 52-59 deg temps at the vents on warm days but truth be told those temps in most vehicles would indicate something being wrong with the AC, like low on Freon. The fact that blocking off heater core flow provides close to normal AC temps tells me that there is a blend door problem. The heat from the core is blending with the cold air from the evaporator and hence blowing blended war and cold air together through our vents. If the blend door closed all the way it would eliminate the warm air from passing by hence why when we block of the heater core hose we stop that warm air from being able to blend. That’s the only possibility. If we blocked off the heater core and still didn’t get low 40’s then that tells us there is something else wrong in the system, but that’s not the case.
You've got it right, every human has different temperature thresholds and comfort levels, so one person's cold air is another person's lukewarm air. A thermometer is the only accurate, consistent way to judge.
That said, comparing one vehicle to another side-by-side, even it's just by the feel of the air coming out of the vents, can tell you a lot.
Of the eight or so 2019 Ram DT 1500s I've tested, only ONE had what I consider to be normal, acceptable cooling performance.
One thing I do if I don't have a thermometer is hold my hand right in front of one of the center vents in the dash and count the time to when the air coming out of the vent begins to feel acceptably cool. ("1-one-thousand, 2-one-thousand, 3-one thousand"...). Every other vehicle I've checked out gets the first feeling of cool air by the count of 5-one-thousand, and very cool air by the count of 10-one-thousand. Seven of the eight 2019 Ram DT 1500s I've checked out are just barely feeling cool at the count of 20-one-thousand or 30-one-thousand, and only the one ever got cool enough to feel comfortable.
Ram definitely has a problem with the AC systems on a significant percentage of the 2019 DT 1500s, either a programming issue or a assembly-line quality issue. Like you, I believe it is not inherently the compressor/evaporator/condenser mechanical system that is at fault.