They are literally making the same exact mistakes, and its leading to the same exact results...karma whoring, piling on, ingroup/outgroup ete etc.
It seems beyond comprehension to me that they wouldn't have thoroughly looked at the rise and fall of Digg and not made every effort not to follow the same path.
Reddit has a strong incentive to make their website a platform where you shout into an abyss that echos back what you currently feel, where you can feel vindicated for downvoting and insulting the "other", and get that sweet dopamine kick for stealing (not sharing) content with no concept of attribution. All of that means higher engagement of the userbase.
If they wanted to encourage thoughtful discussion? That would mean requiring long-form posts, or throttling how fast users could comment. Wanting high quality discussion would mean encouraging posting sources and taking time to read them, which drives users off the site. It would mean dis-incentivizing the emotion-based vector for buying gold as a means to super-bump arguments you agree with, or to spite the opposition.
I haven't seen them make a formal system whereby publishers can pay to have their content autosubmitted and promoted to the front page. That was what killed Digg.
I thought Digg's vote system was simply being gamed by bad actors. The idea that someone at Digg thought it would be even a reasonably good thing to have the system you describe is totally bonkers.