Valve specifically drew Nintendo's attention to the presence of Dolphin Emulator on Steam
I'm sure you've already heard that Nintendo has blocked Dolphin Emulator on Steam, allegedly because of the DMCA, but as it turns out, this is not the whole story. According to The Verge, which was provided by the Dolphin development team, Valve helped Nintendo draw attention to the Wii and GameCube emulator on Steam and unilaterally blocked it without giving Dolphin developers even a chance to defend themselves.
Valve itself does not deny this: "Given that Nintendo has taken action against some emulators in the past, we took early notice after the Dolphin team announced that it would soon be available on Steam," Valve spokesperson Kaci Aitchison Boyle tells The Verge.
Also, copies of emails from Nintendo's lawyers to Valve have recently surfaced, where the Japanese company makes a simple "request to remove the DCMA", so Valve did not give Dolphin the opportunity to defend itself.
All in all, the situation looks a bit strange and confusing, but Dolphin fans have nothing to be sad about - the emulator is still available on the official website of the developers.
Source: The Verge