I am not looking for an argument, and I am always happy to agree to disagree if necessary, but I don’t believe you have grasped my point so I would like to have one further try.
I would accept that an assistant is almost never in the best possible position, and that even if they are, it is close to impossible to judge accurately when the ball is played, and at the same time judge the relative positions of the players. In consequence, mistakes will always be made, close decisions will be close to guesses, and this is one of the reasons why I would support development of the automated offside system that we first saw in the World Cup. It represents one of those areas where technology, if not already, must be close to being in principle clearly better.
But there is still a difference between the current offside law and the proposed change. Under the current law, the decision is limited by biology, by the ability of the human eye and brain to judge two things that they can see but that are happening in different places simultaneously. But at least they can be physically seen. To give a correct decision under the new law also at times needs to defy the laws of physics, requiring an assistant to judge something they can’t see. That takes impossibility to a different level.
Of course, there will always be situations on the field of play when even with three (or more) officials some incidents will simply be out of the sight of any of them. But it’s probably best not to rewrite the laws to make such an event more likely.