Typically when I don’t rate a game, it’s usually because it’s hard to get running on my machine; like if it requires installing a specific version of a compiler that isn’t in apt-get, or if it needs a newer version of OpenGL than my machine supports. The jam description specifically recommends web builds because then it’s easier to get people to run and rate your game. But in practice, sometimes games with web builds still don’t get that many people to rate them.
In previous years we’ve had a rating period of only 3 days; that usually felt like it was difficult to try to play and rate all the games in that time. That’s why we expanded the rating period this time around. I personally felt like it was much better; I didn’t feel rushed. But as you note, overall it didn’t make that much of a difference, so I suspect the actual problem is probably not lack of time? I don’t know.