Being somewhat familiar with ice hockey cause my kid plays, and having read the description of this offsides, ice hockey is much easier because you check position of the skaters relative to the line at the same time as the puck crosses the line. My kid's league has instant offsides, so you don't have to keep track of potential offsides, but you do have to allow otherwise offsides if the defenders put the puck in.

Under IFAB law, you have to keep track of where the potentially offside player relative to other players is at the time that the ball is kicked elsewhere, which means having eyes focused in more than one place at once. Not an easy job.