I don’t know about that in terms of not being reliable. I think they are, but I think they’re also very costly to fix without the warranty. It’s also fair to say, every model year has different tendencies posing problems, and some issues are more prominent depending which model year that was. Just because your 2017 GTI was overheating, doesn’t mean it was a widespread issue that was happening to the majority of GTI‘s.
I Remember when I purchased a Taurus SHO, [which is a TwinTurbo 3.5 L V6], I had others telling me that the turbos would fail, the timing chain will fail at XYZ miles, and guess what? Never happened to me on two of those cars now that I’ve owned.