Why do Players now Write Down the Moves in OTB Chess?

Why do Players now Note Down the Moves in OTB Chess?
The players at the Candidates write down the moves but they can just find the game from literally anywhere on the internet.
Why bother to write down the moves at all?

@Dragon-Emperor It's a chess culture. I agree that they could find their games anywhere but suppose a player like me plays an OTB tournament I would have to write down all my moves. Hence, to follow this chess culture all chess players(even at the top level) write down moves after making the move.

Easy answer: It's in the rules of fide (sort of) under article 8: handbook.fide.com/chapter/E012018
More sophisticated answer: You need to have a recording of the moves to make claims for three-fold-repetetion, 50 moves, etc., at least in long time controls. In theory, electronic recordings of moves might be allowed, however, that might fail and you cannot use 8.1.2 in combination with 9.2 or 9.3 in that case

As a general rule of thumb (goes also for every day life): You (!) mind your own business, and you should not rely on others "anywhere on the internet" to do things (accurately) for you.