Lose talent because of contract roles - Marketing Zillow Employee Review

I had a great experience at Zillow and echo the great things that have been said about it. One of biggest cons I saw was for the contractors at Zillow. I started on a contract myself and it takes a long time to receive an offer to go full-time at Zillow. I would not deny that the 6 month contract is a great launching place but the lack of healthcare (many staffing companies have crappy or no benefits), the lack of job security, and the uncertainty about getting hired on is tough. Most of the contractors I spoke with shared my opinion. I saw so much great talent leave Zillow and find employment elsewhere after 10+ months because they weren't getting hired on and needed to make more money than the hourly rate that contractors receive after the agency takes a huge cut. Great place to work but if you still have someone on your team after 6+ months, as a manager, you should be pushing to get them hired on. With the rate at which Zillow is hiring, why aren't contractors getting offers?