Nintendo's lawsuits they won against emulator projects in the past had donation systems as one of, if not the sole main point they drove to win the case.
From a practical perspective, they "won" in their recent attacks on emulation by shutting big projects down, but we can't know what would have happened at trial because they never got that far.
NoA sued the Yuzu devs and settled out of court, with the devs paying $2.4 million and shutting down the Yuzu and Citra projects. The $2.4 million was noted as being a reasonable estimate of what Nintendo's lawyers would have billed if the case went to trial, not a reflection of Yuzu's collection of donations.
NoA used some combination of carrot-and-stick to get the Ryujinx developers to shut that project down as well, but we won't know what that combination was because they never filed a lawsuit, so there are no public records, and there was likely an NDA.
FWIW, while Dolphin doesn't accept donations, the non-profit foundation behind it has been collecting money for almost 15 years via ads and referrals. All of the financials are transparent: https://opencollective.com/dolphin-emu
I suspect you would quickly attract a lot of the wrong kind of “developers” the moment a financial reward appeared. Especially now that it’s so easy to use AI to make something that looks slightly plausible.
Although I suspect the other sibling comment is the real reason.
