To grow faster and disrupt the market. For a while it was more than a simple commission: it was 100% of the revenue for a whole year. They were also offering one-year free rent to new customers.
It makes sense for Adam. Schmooze the real estate agents with WeWork money so they find you nice deals and get you priority bids, buy the property at this nice discount, lease the property to WeWork. He's winning all around, spend money that's not yours to get equity that is yours.
Why did they do this?