Technically, playing on a real board is considered an "artificial aid" in Live chess, but since there is no way to check; no one really cares. It does slow things down a bit obviously. Lots more players probably use a real board in correspondence chess ("Daily"). Back in the day, I used to have 6 to 8 boards set up around the living room with each of my games displayed.
Playing online with a physical board?


I'm fairly certain that setting up a physical board while playing online is only legal in Daily correspondence-style chess, but considered cheating in Live games.

I do but I play daily only. I find I play much better in 3D than 2D and have depth issues when looking at screens.

Regardless of the time control- many games come down to a time scramble in live chess. It is impractical to be using one - a disadvantage. Sooner or later in live play- all players eventually adjust to viewing only the screen. Best to start now.
CC highly discourages the practice- but can only suggest a guideline- as the practice is undetectable and therefor unenforceable. Hence, any such “rule” can not be made. This does not translate to “It’s completely OK - no problems exist”.
To say “nobody cares” is incorrect.

- Help from other people - You may not ask for help from another person! Do not ask anyone for advice on specific ongoing games! Do not let anyone else play on your account!
- Books, opening databases, or any outside help at all! - For Live games on Chess.com, if you are looking at anything other than the game in front of you, you shouldn’t be! Focus on your game, and play with your own mind and strength!

“Any outside help at all”
https://support.chess.com/article/317-what-counts-as-cheating-on-chess-com

For Live play -In interest of fair play- A 2nd board requires every move be made 1st on the 2nd board and then made exactly the same on the screen. Highly impractical when confronted with time constraints , which happen in any time control. Inevitably, in the process of moving a piece on the 2nd board- it may become readily apparent the move hangs a piece or worse. In the interest of fair play the move must be entered - no takebacks. An unnecessary position to find oneself in - especially new players. There are several such issues with using a 2nd board that could unwillingly cause concern.
Adjustment to 2D is harder for some but eventually gets made. The disadvantages (extra time, distraction, etc) are far greater than any perceived help.
I played as a kid and now as an old dude looking back into it. I definitely get the issue of how the brain sees 2D versions vs over the board differently. But I don't understand why it's "unfair": people will adapt to whatever they play the most (unless there is data from real studies that show that people playing with physical boards have a performance advantage over those who do not?). I've read through the thread, but the only thing I can see that makes sense as a critique is that it might disadvantage a player actually using a physical board.
There are now also electronic boards that sync with Chess.com and other sites (was looking into getting one as it seemed cool), so that even the delay bit is gone. Make a move on the physical board, the move is immediately reflected on the online board. If one uses on of these, it seems the issue of time delay is removed.
Sounds like a dumb question I know. But it’s been many years since I played face to face. But 2D versus 3D on a screen and playing with a real board are all different experiences. I found if I was playing in 2D a lot, I’d make rubbish moves face to face because I wasn’t used to playing over a real board and I was missing things.
I hope that makes sense. I’m considering buying a real board.