Because you'll get lost in a whole discussion of discrimination, if it's Airbnb's responsibility to prevent, if homeowners have the right to discriminate. If Airbnb is even legal, etc, etc, etc.

(For example look at some of the comments in this thread that are talking about discrimination, when the topic is ostensibly arbitration. It should be two separate discussions.)

Either talk about it in a Vacuum (without any particular company), or at least pick a case that is more "pure", i.e. unequivocally the company's responsibility.