So you say. But it's not up to you to decide. If Nintendo don't really 'know', and could actually sell more games by letting people play free copies on their PCs, then it's their choice to not do so.
It is their choice yes - but what they actually own, what they can exactly do about it, and who they can target, is all limited by law.
For example, if your neighbor plays music too loudly for your comfort, you have every legal right to complain to the landlord or maybe even press charges, but you can't kill your neigbor, cut their electricity, or attack the company who manufactured their audio equipment, or the one who installed their TV set.
Similarly, the only thing Nintendo can legally do something about is to attack those who distribute the game cartridge images (rom files) because those are copies of copyrighted software.
Meanwhile,
emulators, as long as they come without any games, are just completely legal, like your neighbor's audio equipment, even if it can be used to play illegally obtained content.
Similarly, making gameplay or emulator videos on Youtube is completely legal.
Making fraudulent DMCA takedown requests, on the other hand, is, AFAIK, an actual criminal offense: the "cure" is worse than the disease, especially because it attacks different people than those actually responsible. People downplay the seriousness of this, but it is actually a pretty big deal fundamentally. Our Western societies are built on the idea that independent authorities (police, judges) decide if someone is guilty, and only said authorities can limit our freedom of speech, and even then under very strict rules. Laws like DMCA (and similar laws elsewhere) shifted this responsibility to individual private companies; similar to you actually
having the right to kill your neighbor, for a good reason explicitly specified in law (e.g., neighbor attacking you and you acting as self-defence). To compensate for this shift, it was made illegal to misuse this power - obviously. This is equivalent to you killing your neighbor when he actually
did not attack you - try and see what happens.
Yet, large companies do fraudulent DMCA actions - criminal offenses - all the freaking time without getting prosecuted and convicted. And even more weirdly, there are people on the internet who try to justify these actions with some mental acrobatics. This just demonstrates how ****ed up society we live in.