I would disagree. There's a point where code terseness and abstractionlessness come at the cost of code readability, and these competitions cause you to go way

I would disagree. There's a point where code terseness and abstractionlessness come at the cost of code readability, and these competitions cause you to go way beyond this point. There's no sense in practicing how to write confusing code that is very short, other than the problem-solving aspect of it. I think code golf is just another form of a puzzle. So, whatever benefit you get from solving a puzzle, or mind bender, or whatever, you'll get from code golf. Hopefully you'll have the sense not to golf production code.