My point was, not being on Steam does not prevent good freeware games (or mods so huge that they could very well be standalone games) from being made. It does not prevent them from being developed nor from having a dedicated following. It limits their userbase, so what? They're free games, they do not need sales to stay afloat. Being prevented from getting on Steam will not prevent such projects from appearing. There would be no harm to the project from not being able to put it on Steam. Barring truly freeware games from Steam won't stop people from making them.
Dedicated fans of the genre will find those games, like they always did. Non-fans won't be exposed, true, and a fair bit of casual fans might end up missing out, but this does not kill projects like that off, as far as I've seen.