First of all, I really appreciate how much thought you've put in considering this feedback.
So it seems there is two issues (or consideration) at hand: How to make sure rating doesn't get too concentrated to the top 1% and how to make it easy for people to engage in the voting.
To be clear I don't think the current system is that problematic so we discuss mainly on how to improve it even further.
- How to make sure rating doesn't get too concentrated to the top 1%?
Let me try to break down this one even further. I think it all come down to how to have a fairer distribution of game played. If a game is played, ratings will follow, comments, and so on... For new jammers the rating might not be important (and sometimes discouraging) but having positive comments can encourage them to continue participating in jams. So actually it could lead to a multitude of solutions like a optional queue system that would prevent user to pick the nicest thumbnail, or pre-installing game if you have the app...
The fear is that the voting period is the only few days many games will have the chance to be played. After the result come out, most interest will be focused on which games were the most interesting to play. Only a tiny minority of user will start to explore the submissions. So the voting period is a crucial and exciting period to have your game played by strangers.
At first I agreed with you that it is not a zero sum game. Yes a user rating a popular game doesn't mean they will not rate something else. However after sleeping on it, I start to change my mind again. Time is limited and time spend on a popular game is less time that could be used on other games that would need reviews. I struggle with that myself, I have a massive list of game I would like to play. A lot of them are popular already and I feel really guilty to not be able to spend more time on more confidential games.
To be fair the popularity aspect was there before the Popular filter. I am lucky enough to have a game that got a lot of downloads (I think mainly because of the thumbnail) and I don't see in the analytics that it changed anything to have now the Popular filter.
- How to make it easy for people to engage in the voting?
I agree that having an easy entry point is essential to help people engaging with the system. The counterpoint to that is that the Popular filter is actually an option and as a result will be overlook by the vast majority of players especially the one not familiar enough with itch.io.
And if they start playing games with the popular filter they will probably to continue (especially for GMTK with so many entries), there is even fewer chances they would decide to explore games randomly. Not impossible of course but unlikely.
To be clear I am also of the opinion that only the participants should be allowed to rate games during the voting period. (someone who didn't participate can still rate and comment on the normal game page). I have also the impression that non-participant comment tend to be less encouraging because they don't have the same perspective than participant. So in general I would pay much less attention to these users. You have of course a totally different point of you since you need to consider this specific part of the site but the whole website experience.
In conclusion
After thinking a bit more about it, I would say that having the Popular and Most rated filter has probably very little effect. If there is an effect I still believe it would be more favorable toward already popular games. However it has an effect on the jam participants that already struggle to get their game played and seeing these options feels unfair. Not having the filter would feel much more balanced during the voting period as all title would have the same discoverability. (so in the end I think it's amore about feeling than actual user behavior)