The voting system itself is the biggest problem. You drown out discussion because people are much more willing to upvote stupid pictures than they are long articles.
I don't disagree, but the difference (a big one) is that there is no "main page" that gets corrupted by this easy to digest content. If you want to have a feed of longer form reads you can follow #goodlongreads or better yet, follow a user that doesn't post or share easily digested content. -you're good like that. mk too and any numbering others. So it's the voting mechanism in conjunction with the way content is presented that is the issue.
The feed you see when you're logged out or not following anyone serves as the "main page" equivalent, and it's just as susceptible to corruption as reddit's /r/all. For years people said the same thing about reddit: the easy-content corruption didn't matter because you could just follow different subreddits. But even among my followers, it seems people vote more for agreeable short content rather than long content.
I think that in a lot of ways Hubski's architecture is more akin to Twitter than it is reddit. Nobody goes to twitter to see a main page. Right now we have a very small site but if it were to grow those global pages would become pretty meaningless IMO. You would have to construct your own feed. You could seek out those posts you deem high integrity and follow others that feel similarly. Is this going to eliminate the occasional puff piece being shared in to your feed? No. We're humans, we like candy even if we say we only eat healthily. You been on Hubski IRC lately? I've been stopping by randomly but nobody is around.
The voting system is not at fault here. It's the community. The bigger the website gets (and the more attention it draws) more people go towards it. Reddit has a lot of 13/14 year old kids who only "upvote stupid pictures" . The secret to Reddit is finding the correct subreddits and contribute to them.
The voting system is in a sense at fault. Examine the algorithm: 
. In the time you can read a reasonably long article worthy of an upvote, you could rate at least 25 images. Because of the nature of the time fall off inherent to the algorithm, human's natural inclination to keep hitting the dopamine button and that you can only give one upvote rather than rate content out of 10 or 100, pictures will always dominate over words as content.