If you’re going to use Steam’s Curators’ List or Steam Broadcasting service to promote a product and someone’s paying you – whether it’s in money, games or Trident Layers – you must clearly disclose this to your audience.
Valve made a number of changes, spotted initially by the Steam Database twitter feed, to the Steam Subscriber Agreement, but this is the biggest among them.
As noted by Gamasutra, this change matches up well with the disclosure requirements the FTC puts on paid YouTube personalities. In cases like these where someone makes their living entirely by promoting things, transparency like that is important. It lets potential fans make an informed decision about whether to trust that endorsement and whether to trust the personality themselves. As the Curators’ List and Steam Broadcasting get more popular, this is a good move for the service.