It implies that you do not get absolutely 100% perfect allocation where everybody is maximally happy according to their constraints which is what "efficiently"

It implies that you do not get absolutely 100% perfect allocation where everybody is maximally happy according to their constraints which is what "efficiently" means in that context. That is also a useless and impractical standard to hold any system to as any optimization problem is impossible if you have missing non-degenerate constraints/information. In practice, the question becomes what systems result in the best outcomes given normal conditions and information. As a example, we see that total command economies are dramatically worse than markets at normal amounts of information. Alternatively, how can conditions be changed in normal fashions that can be consistently enforced to maximize system outcomes. Things are further confused by the fact that we have a very poor understanding of even the implemented systems. What aspects are important, what are not? For instance, we can see that the modern Chinese economy is clearly more market-driven than previously, so the increased amount of market economics has been a dramatic improvement. Clearly, they were previously on the "too little market" side of that equation. In many ways, their markets are more "unrestricted" than the USA, but in others less, are they more market-driven than the USA or not? Are the ways in which they are important, are the ways in which they are not important? About the only thing we can really categorize are directional changes from a previous status quo and maybe we can categorize transformative impacts after the fact. It is these sorts of questions and observations that matter. Quibbling about how a system is imperfect in a wholly impractical limit to argue against practical matters is just silly especially when those same problems are held by literally everything.