I like rating the games I play on this site, specifically ones with less exposure. I feel like I'm helping it be seen by more people by giving a good game a 5 star rating. In the case of the thousands of less impressive games out there, I don't feel like It's doing much for the system to give a game a 1 star score. Anybody have any idea what effect doing so has on the itch.io content filter system? Will it make these games harder to find?

The popularity algorithm is deliberately obfuscated, so people don't try and game it. That said, 5-star rating systems are controversial as a general rule, it's just that nobody could seem to come up with something demonstrably better. All we can do is rate according to our conscience. I don't remember ever giving a one-star rating to anything. Two stars, yes, rarely. But other people seem to delight in doing that sort of thing. Not on itch.io, however. Ratings being only visible to the creator might have something to do with it. But we won't know for sure until that changes.