Yes, that's very true. In the case of the Pentastar, it's also the weak vane-type variable displacement oil pump that's a concern. It defaults to pushing all it can when you start the engine, then the computer switches on a solenoid that cuts the oil pressure down to less than half. However, it struggles with oil that's too thick.
Without data, I'm just a person with an opinion. The same goes for you. I don't have any additional data to support my opinions beyond the published engine specs I talked about earlier. What I do have, however, is practical experience with the Pentastar engines. I didn't even get to try 15W-50 in one, because when we tried 15W-40 in one, it idled very roughly; the engine was struggling with it. It's one thing to debate theory and opinions, another to try things in practice. A 15W-40 is considerably thicker than a 0W-40 or 5W-40 when cold. The Pentastar just can't run it. It's even worse if you're in a cold climate. Never mind a 15W-50.
Now, if we're talking about a HEMI, that's entirely different. A HEMI will be able to run a 15W-40 or 15W-50 without issue, within the allowed cold temperatures specific for a 15W-XX motor oil. The Pentastar is a cheaply made V6 engine that has a lot of limitations. It was designed to make Chrysler a lot of money, without any regard for how long it lasts or what kind of hurdles owners have to deal with. Just try replacing the oil filter housing on the PUG. The job can make a grown man cry because of how careful you have to be with all the brittle plastic bits that you can't buy from Mopar. As a bonus, they attached the fuel injector harness to the rear bottom of the lower intake manifold using a fir tree zip tie that you have to cut and then pull out. If you're doing the job on a RAM 1500, Jeep GC, or Durango, you will get mad trying to get that off without damaging anything.
The Pentastar has all the disadvantages of a HEMI engine, without any of the advantages.