We know why Dolphin wasn’t put on Steam.
- Dolphin ships with a decryption key for Wii games
- Valve’s legal got worried about hosting that, and reached out to Nintendo
- Nintendo did their usual thing and said no
- Valve pulled down the Dolphin page on their own, without a legal demand from Nintendo
Valve continues to host RetroArch and the various cores, so it’s not like they’re opposed to emulation in general. The ability to copyright “magic numbers” in the US (Valve is an American company) isn’t up for debate, and it would also put them in violation of the DMCA, so it’s not hard to see why Valve would be worried about this specific emulator.
As for Dolphin, they have options:
- they can choose to keep shipping as-is, without being on Steam
- they can choose to add BIOS support and sidestep the entire question of decrypting keys
- they can require users to enter their own decryption key they dump directly from their consoles (which, realistically, means that users would get one off the web separate from Dolphin)
I have AA (via their bundle, it’s not really worth it on its own), and within a few weeks I wasn’t able to find online matches. It also didn’t feel great to play (both on touchscreen and controller), and they never released anything beyond 3-on-3 hockey. I would not recommend.