The lino is paid to make these decisions. He is also in the best position to see the offside. Stones is in the middle and has to turn his head both ways. He has to react no matter what he thinks. Because if he is wrong, he would be responsible for not reacting.
Not seeing a flag means he has to make the tackle.
The lino knows VAR will bail him out if wrong.
I remember a certain United player being completely offside last year. The players didn't react properly because he was so obviously offside and interfering with play.
By the time they did react, it was too late.
So players are always going to do their job until the whistle blows.