In this particular jam, apparently, it will be like that, you "win" if you submit something, even if it isn't polished nor finished, but a lot of jams have turned into competitions with no prices, just a recognition that has no purpose nor use.
Viewing post in Team sizes
I would correct your statement from "lot of jams have turned into competitions with no prices, just a recognition that has no purpose nor use" as more like "lots of jams have turned into competitions with, as main goal, quantify the quality of the work and the skills of the developers involved". Nothings speaks more when job hunting in the field of the video game industry than a portfolio filled with contest-winning works as it shows dedication, skills and the ability to work and reaching a goal under a tight deadline.
In fact, there are head-hunters out there that are following any serious Jams for medium and big developing studios. Depending on cases related to the jam, it's not that rare for devs that display high rated skills to get contacted by those people. (It does requires that a dev jam developers have properly setup his profile and contact info, obviously.) In those cases, it's not much of a case of "who wins", but more about who seems to be exactly what a certain studio is looking for.
Another approach of the jams is that it's actually one good way of promoting an early PR for a new project. Obviously in this case, a 10-days devs jams isn't really enough to make a long-term oriented project, but any 2+ months jams with any form of professional and well published coverage can do wonders at bringing a crowd for the launch of the actual full game. When you win a dev jam with a project that has potential for an actual commercial release if worked on further, it's one of those choices you got to serious think about.
Obviously, in the end it's all about having fun anyway, right? And some people have more fun at competing and winning than doing the actual tasks to compete, hence why eSports have become a lucrative thing. The same exist within the devs community where winning a dev jam is just another way of feeling the adrenaline rush of a victor.
Perhaps you are right, perhaps the purpose of a competitive jam is to quantify the quality of the work and the skills of the developers involved, but also, as you said, it's not really that helpful, head-hunters look for specific skills, not winners, same for publishers, they look for games that have a community around them, winners might have the vote of the people, but not necessarily their full interest.
I'm not saying competitions are bad, not saying they aren't fun, they are for certain people, but having that mentality all the time can be detrimental, I've seen people that are so focused on winning that they forget to build a network, and having a huge network will open up way more opportunities than winning jams.
[Edit]
I'm not implying that you should never enter a jam with the sole purpose of winning. What I'm trying to say is that your mind should align with your goals, if your goal is to win game jams then, by all means, do that, but if your goal is something else then consider what kind of mentality would benefit your goal the most.
Some people fall in love with their concept so much that the prize condition is having been popular enough to continue the project outside the jam. There have been a few games that released to decent or great success that originated as jam games.
I of course would relish that but am also realistic. I need more experience first.