We have all played with him. The guy with his shadow in your line, or with the practice swing you can see out of the corner of your eye. Not to mention the jingling pocket change. They usually set the flag down a little too close to the hole.
Moving a ball mark may be the easiest distraction to avoid. The rules of golf offer refuge, allowing the mark to be moved such that your putt line will not be affected. Unless you miss-putt and hit the ball mark anyway.
We love the old black-and-white footage when marks were not permitted and you could “stymie” or leave a ball in the way as part of the game. Mashies or wedges were used to jump over a blocking ball. The films always show the successful shot.
What about the sculled attempts, or the divots taken near the hole? We never see that footage, but using ball marks is a much better play.
Until some joker takes out a manhole cover or Vegas chip he has been somehow carrying all day, and marks it in your line. Move it, friend 2 to the left!