What I am challenging is this very premise....that creating a simple and well working encounter design system for 5e is impossible. Because as we know thereout history, "all things are impossible....until proven otherwise".
Then prove otherwise. The fact is that, so far, there's not even a hint that it might be possible...
Is it very hard....clearly. Could it be impossible....it could. But the point of the critique is to let the designers know "hey when you all are thinking about improvements to the game....when you are thinking about 5.5 and 6e.... you should pay some attention here because this is a weakness in your game that may be improved". And by gum is a designer has a eureka moment, and does figure out some cool way to get my cake and eat it too, then the game will be even better.
And, once more, you are totally mistaken about the designers' intent. Even if they might make the game "better" according to some criteria, if the solution is complex, they will simply not work on it because they don't want to create a complex game full of rules and sub-rules. At some level, not only is it not worth it to please a small subset of their player base, but it would make the game much too complex overall and displease the much larger fanbase that they have gathered with 5e by making a game which is not designed only for the geeks.
As for me, I agree that it would not make the game better, and I would actually bet that whatever system would come out of it would still be criticised heavily. You know why ? Because, at the core of the system is the fact that the NPC/Monster creation system does not wield exact results especially at high level, because it's just impossible to predict whether an ability will prove overkill or be a complete dud depending on the situation and the characters facing it. So it would require a complete overhaul of the monster design system which would lead along only two possible roads, totally open but insufferable in complexity like 3e or totally controlled but totally closed as well like 4e. So another impossibility. And even that overhaul would fail if the abilities of the PCs did not suffer the same treatment.
In the end, it's just contrary to the entire design philosophy of 5e and it would be ridiculous to have a complex bubble just for this while the rest of the system stays simple and streamlined.
But once more, prove me wrong, I'll be waiting for something more than "impossible until proven otherwise", but I will bet you whatever you want that it's not even close to being in the radar of the designers.
There are imo two kinds of critiques: Critiques in the spirit of "I hate this and basically want my money back" and "this product is so good...but it could be better". Mine points towards the latter. Feedback is a critical component for designers to iterate and improve, and so this remains one of mine.
As long as it's constructive feedback, it's much better than your initial stance of "entitled to complain", but the problem is that I don't think that you understand yet how contrary to the game design (and therefore not only technically impossible, but also out of scope) your request is. I have done my best to explain, but honestly, there is not much more than I can do at this stage...