I've noticed this and had similar thoughts. Downvotes on Reddit may hurt our ego but downvotes on Steemit can hurt our wallet and and affect our ability to earn future income. Forum encounters can be contentious and in some cases users will form grudges and obsess over punishing someone instead of simply disagreeing and moving on. This can foster an environment in which participants only feel comfortable providing positive feedback and will censor themselves. I think it's a bit of a double edged sword in that we eliminate some unnecessary trolling and people will put more thought into positive engagement but we can also miss out on personal growth from challenging our ideas. I've considered creating a seperate anonymous account to offer divergent opinions without fear of retribution from large accounts but haven't bothered because user interaction is low and it's easy to sink into the rut of autovoting and collecting income.
"Is it blockchain worthy?" and "Is it upvote worthy?" are also high barriers of entry for commenting. When I joined Steemit I thought it was odd that many users wanted to engage outside of the platform through chat applications but now I assume that is where most of the communication takes place. Users will generally only post items they can affirm are blockchain and upvote worthy. This can be a good culture to foster if the site gets very large - bad commenting can essentially be compared to spam posts - but right now we don't suffer from overuse of the platform and low user engagement can leave this place feeling like a ghost town.