I get it, it eliminates the chance of projecting tells. Well, that’s poker. If you have tells you’re bad at the game. I get many players hone their chops playing online but at an event like this it seems silly that everyone dresses like Darth Vader. The game is all about reading people, watching is all about the spectacle, why eliminate both?
There’s no pressing reason to, and poker players would kick up a fuss.
Of course, for the great majority of players, if not all, it really makes no difference. The game absolutely is NOT all about reading people, at least not if you mean their physical tells. That is a very small part of poker. At almost all levels of poker the difference between winners or losers is based on their understanding of the game’s strategy - mathematics, probability, and game theory. Such reading people as their is is largely reading what they do with their cards and their chips, not their physical tells.
For coolness. Depending on the lighting and the seating, there’s a chance you can see what the fellow wearing the shades is holding in his hand from the reflection in the shades.
I have heard some pros complain about the bright lights that TV tables need. (But that doesn’t explain the use at not TV Tables).
Hoodies have been used for a long time to cover the head and face and now scarves are being used to cover the neck.