I think they vastly underestimate how many things Meta tracks besides ad tracking. They're likely tracking how long you look at a given post in your feed and will use that to rank similar posts higher. They know your location, what wifi network you're on and will use that to make assumptions based on others on the same network and/or in the same location. They know what times you're browsing at and can correlate that with what's trending in the area at those times, etc.
I have no doubt that their algorithm is biased towards all that crap, but these kinds of investigations need to be more informed in order for them to be useful.
While supposedly being a lot cheaper than litigation, arbitration isn't free either. Besides, arbitration makes it near-impossible to appeal a decision, and the outcome won't set binding legal precedent. Furthermore, arbitration often comes with a class action waiver. Valve also removed that from the SSA.
I'm far from an expert in law, especially US law, but as I understand it, ~~arbitration is still available (if both parties agree, I assume), it's just not a requirement anymore~~ [edit: nevermind, I didn't understand it]. I'm sure they're making this move because it somehow benefits them, but it still seems to me that consumers are getting more options [edit: they're not] which is usually a good thing.