But RB are aware of their car's shortcomings and to suggest they aren't is just a simplistic opinion given all the expertise they have. Max has also been very vocal about the shortcomings, which completely disproves any theory it is built around him. It is somewhat like the Mercedes situation has been in the last few years, the car should be good but on the track it isn't and it takes time to understand why this is so. It is clear from comments from Max, Perez and Lawson that the car has a extremely narrow operating window, such as the Mercedes had also, thus it is extremely difficult for a driver to get the car to it's optimum condition and track, ambient and the tyres all are all playing their part in making it tough to get the best setup.
Thing is, as you've stated, if RB give a driver time they are wrong, and if they don't they are also wrong.
But then with some 'F1 fans' they are dammed whatever...