This is it. The line in the sand has to be somewhere. But by moving it further forward you will get more goals and that is a good thing.
To be honest it's incredible that linos get it right as often as they do they need two pairs of eyes and split second timing. Dont help themselves by being 10 yards behind play of course.
A player has to be able to judge whether he is committing an offence.
Under the traditional system, a player who is deemed 'level' is onside, and players can normally judge whether they are more or less 'level' (in other words, a visually acceptable position) themselves, so in general, the rule works.
Under VAR, 'more or less level' isn't accurate enough any more, so to be relatively confident of being onside, the attacker now has to stand partially behind the defender to ensure that his shirt label isnt a millimetre into an offside position. This therefore works against the attacker, when the law is meant to actually give the benefit of the doubt to the attacker.
So, in order to use VAR, but in a way that upholds the tradition and spirit of the law, there should be a certain lee-way introduced into the comparison of the two lines used - I would suggest that a player is onside as long as 'his' line is less than say 6 inches or a foot ahead of the defender's 'line'.
That way, the technology could still be used, but being visually 'more or less level' would remain as being onside....
I have a secondary issue with this rule in that there is now an imbalance in accuracy in the information used. While we can measure the receiver's position exactly, there is no clarity in at what exact point that measurement should be taken - because when kicking a ball, the foot is in contact with the ball for a significant fraction of a second, during which the attacker and defender will inevitably change position (and therefore potentially change from being on or offside). So, should the measurement be taken when the foot first touches the ball, or when that contact eventually breaks?