Unity Technologies has stated that PlayStation, Xbox, and Nintendo will pay the company's new runtime fee on behalf of game developers.
A new FAQ has been shared by Unity Technologies, which answers questions regarding the company's recent change in pricing plan for its game development engine.
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This sounds like it would mean charging Valve money for the privilege of using Valve's own infrastructure every time a player installed a Unity game after a major PC upgrade/reinstall or after uninstalling that MMO they dumped every other game in their library try out.
Steam could probably bake a ban on software that uses installation trackers into their developer/publisher ToS, or ban the collection or transmission of Steam user data related to installations, or something similar.