This is what i mean.
Of course it was close, they were level, doesn't get much closer. A linsman has to keep an eye on the ball to see when it's played, an eye on the position of the last defender and nearest attacker, and other players on the pitch as well in case a foul is commited. And now apparently he has to look at the 18 yard line.
Add to that the movement of the defender and attacker going in different directions rather than standing still like in a freeze frame and it's virtually impossible for a human being to accurately judge if someone is offside or not with the naked eye.
But it's so so easy for managers, pundits and fans to say he should have got it right and to call him crap. So they do.
I'm sure they all reckon nuclear physics is easy as well. Well, it's easy to say it's easy anyway.