I think the question to ask here is:
a) whether someone wanted to vote/review entries, but didn't do it in order to avoid a disadvantage
b) whether someone who didn't really want to vote/review entries would do that in order to get an extra advantage
I expect people from a) group would give some moderate-to-high quality feedback - reviewing is something they wanted to do, anyway. So if there are people like that, then incentive could indeed result in some extra quality feedback.
When it comes to people from b) group, I'd expect them to give low-to-high quality feedback - some might just want to grab the extra points, while others might decide if they do it it's worth doing right. So in such case the incentive could be hit-and-miss - we could end up with more low-effort votes with some people not even playing through all the entries* or playing them very briefly** and/or we could get a few more sets of high quality reviews.
There's also a risk that some people - who can commit to making a Jam entry but otherwise have not enough time to play and review other entries afterwards - might feel demotivated, because seemingly lower-quality entries would end up higher because of the voting bonus. Note: it depends on the strength of a bonus; e.g. a 1st place worth of points could skyrocket some middle-grade participant by a few ranks.
It could be even worse if someone did try to play and review each entry but only ranked about half of these. Then, they either are frustrated the lack of time cost them voting bonus or they succumb to temptation and submit an incomplete-playthrough vote*.
Then there's a matter of
intrinsic vs
extrinsic motivation - right now people mostly vote because of their intrinsic motivation (they want to play through the games and provide feedback). Adding an incentive could risk current voters not getting as much fun from the experience as before, because in their mind it would become a mean to getting a higher score rather than a fun experience in and of itself (it's weird, but human mind can work this way).
I'm not saying "Absolutely not", but I'm also not certain introducing the reward would result in higher quality votes.
One option is to give it a test run during one of subsequent Jams (not the nearest, though, because there'll be plenty going on already) and see how it affects votes. It requires making some design decisions (like Dan's aforementioned issue with teams).
Before that, it's worth looking into other community-voted competitions like GMC Jam, to see how they address the voting participant disadvantage (if they address it at all).
It would also help if many other Jammers gave their input. E.g. asking in a poll:
- "Do you vote in GMC Jam?" with answers: "Yes if possible", "No, because it puts me at disadvantage", "No, because I have no time", "No, because I don't want to"
- "Would you vote in GMC Jam if voters games got ranking bonus?" with answers: "No, for the same reason", "No, because I don't like this system", "Yes, but not for reward", "Yes, because it gives me an advantage"
I guess one takeaway from all that is that incentives are tricky, and might or might not give the results we want. ^^'
*As I see it, the reason we don't have a voting system debate every single Jam anymore is because most voters (if not all) actually do play through each entry. Otherwise, we'd keep seeing the anomalies with some consistently lowest-ranked entry being above some others, because it got ranked 10th by a person who played 10 games and 15th by a person who played 15 games, and others ended up played more rarely. Then again, maybe with convenience of the Jam player even low-effort votes would cover every game?
**I don't have anything in particular against people playing the game only for five minutes or so, especially since it's still quite a commitment when multiplied by number of entries. However, as someone who tends to make longer and not-as-flashy entries I'd rather avoid breaking the current balance between people who are thorough in their playthroughs - playing most games to conclusion if there's one - and those who get the gist of the game based on 5-10 minutes of gameplay and base their ranking on that.