I've seen a number of people make this kind of argument, but it's a bit of a strawman. Nobody is saying that there is a solution that won't produce tight calls, but I think people would be more accepting of a decision if they can visually see a gap between attacker and defender, rather than seeing two coloured lines and taking for granted that the computer operator is getting it right. Especially as there is a known margin of error of up to 15cm.
Check out Millwall's equaliser against Fulham from midweek for proof of why VAR checks for offside are needed in the game in some form. Also, from our game last Sunday, following Henderson's second half save the Bournemouth player who picks up the loose ball was yards offside, but was allowed to play on and win a corner.