In fact, all advanced players have some level of skills for blindfold games, which come from the accumulation of long term chess training (not specifically blindfold). Even if they could not see the whole board, they can clearly see the small part of the focus, most times involving some tactic combination. They can continue calculating in their mind without looking at the board.
This is what our Tactic Workshop training targets for.
Blindfold training helps strengthen our vision. We can see more with or without board. We can see them quickly and intuitively. This is critical for everything else, including calculation or strategy planning. If we can't see, we can't plan or calculate. If we can't see a few moves deeper, we can't calculate fast enough, then we will get into time trouble often.
Playing blindfold is interesting. Some top GMs have amazing capability to play 10 to 20 games blindfold simultaneously. They have unimaginable powerful memory.