Twitter doesn't have downvotes so its a little better in that regard.
The common "EDIT: <<apology or excuse here>>" I saw on reddit screamed of insecurity instead of people standing their ground. That mentality is bad for young minds.
The point was to discuss how Reddit, Hacker News, and other message boards utilizing pseudonymous voting are not monopolized by brands, celebrities, and businesses in the same way that Twitter and Facebook are. The discourse is still more egalitarian than the alternatives, and it isn't these traditional cultural leaders that dominate discussion on Reddit.
This isn't to speak on issues of astroturfing, echo chambering, or misinformation, but these aren't relevant to the discussion, and aren't unique issues to Reddit.
How much of that is simply due to the nature of the product?
Reddit would very much like to have the brands, celebrities, and businesses, and influenced their change to allow users to post to their own profile pages.
For example I think reddit played a MASSIVE role in the rise of PC gaming in the last 5 years. It's more indirect, admittedly.
Democratized voting systems on pseudonymous platforms can have a content curation effect while limiting this accumulation of social capital, as seen on Hacker News and Reddit. You don't see quite the same level of brands and people building their clout on say Reddit the way they do on Twitter. Conventional cultural leaders like politicians and celebrities don't dominate discourse on these platforms to the degree they do on Facebook and Twitter.