Next to nothing in benefits perhaps.

But once you give Gold status to Globalists, you automatically start giving AA miles on each paid Hyatt stay. Somebody pays for that - whether it's Hyatt, AA or a combination.

Since my Oneworld status is elsewhere, the only benefit of AA status for me is those thousands of AA miles from Hyatt stays - nice to have, but not worth enough for me to aim for AA status. But multiply me by every other Globalist who collects AA miles but doesn't care about AA status, and I suspect you'd end up with a cost figure well into the millions for no added benefit for either company...