Trevor benefits because he gets a sponsorship and has a chance to sell more discs. DD benefits because they get extra exposure and a chance to sell more discs. Discraft may not care because they are a powerhouse and immediately sell anything they produce, but I don't see how it benefits them.
There was a recent announcement about some Bro/Beth molds only being available on the Discrasft site and not on Foundation, maybe this is simply a way to further separate the public perception of Discraft & Foundation for legal / existing contract reasons.