I think people should have the ability to create custom boards in ducks race. They could invite people to play them, share them with friends, and request them to be added to the official boards list pending a review or community vote.

I think that would take too much time. You need to know coding and then test them but not sure

Hello,
I think the main problem is that usually, new Duck racing boards introduce some new mechanics, not just existing features repackaged under different layouts/square names.
For instance, the anniversary board introduced the concept of evil cards, the casino board introduced the slot machine/roulette/Black jack squares along with new cards, etc... For this to work and be interesting, some kind of basic scripting would certainly be needed.

Personally I see the interest of your suggestion, it would also be fun for me to do this with my group of friends and create some interesting board with a cool story or theme behind it, but once 100 people do it, it's no longer interesting, you just have a bunch of mostly the same boards with slight differences here or there. Part of the game is also memorizing the board layout so that you know where to drop cards/what to do to make the most out of them, and if you had to learn some new board someone created as soon as you join a game, it would slow it down significantly, and this is already usually quite a long game.

Of course that's not even getting into the fact that you could easily create potentially highly offensive boards, but that's an entirely separate issue. Allowing custom content in an online game can be quite tricky, probably everything requires a review in reality. Of course, I again say that if I am playing with my friends, we know what is offensive to us and going over the line is quite normal in that case, but nobody can really guarantee people will use that responsibly and will share potentially offensive items with their friends only.