This has always been the case, and is really the main practical advantage of open source. Contributing code back is an act of community service which people do not always have time for. The main issue is that over time, other people will contribute back their own acts of community service, which may be bug fixes or features that you want to take advantage of. As upstream and your own fork diverge, it will take more and more work to update your patches. So if you intend to follow upstream, it benefits you to send your patches back.