1) Those asserting arbitration is a scam or otherwise unfair. The company whose TOS you've signed is the one paying the arbitrator, after all. This system is designed for you to lose.
2) Those with personal anecdotes about going through arbitration, who had a decent-at-worst experience, and ended up winning.
If there's one thing I've learned from the internet, it's that positive outcomes generate a light breeze, but negative outcomes generate a storm. If arbitration was inherently unfair -- at least as often as we seem to tell ourselves -- I'd think I'd see more anecdotes about it. So far I've seen zero. Maybe that's just "luck", but I figured I'd ask, directly to the community whose discussions about it prompted to this question.
Disclaimer: I'm not a fan of the de-facto forced arbitration imposed on anyone who doesn't want to (or can't) run their own email server, etc. I've been deeply dismayed by the last few SCOTUS decisions on this subject. And yet I haven't come across an anecdote of anyone getting boned. Indeed, in my own social circle I know 2 folks who have been through such arbitration. They both assumed the deck was stacked against them, and they both emerged victorious.
