If you and your friend get into a argument over something on the playground, instead of going to a teacher, you both agree to tell your stories to another friend you both agree will be impartial. You then both do what that friend says without involving the teacher.

Instead of Steam forcing any disputes with them to go through an “impartial” 3rd party company they choose and pay for to oversee and rule on disputes, they are saying that disputes must go through the courts.

Basically forced arbitration has always been seen as anti-consumer and unfair because the company is paying for the arbitration and is thus considered more likely to be found in favor of. Steam is doing the opposite and as such this is seen as pro-consumer and a good thing