A study found that users who receive negative feedback on their posts tend to contribute more frequently, but their subsequent contributions are often of lower quality.

Additionally, there were concerns raised about how downvotes negatively affect new users (who aren't aware of a community's norms, and so are more likely to collect downvotes), and how downvotes stifle diverse viewpoints, helping to create an echo chamber (the so-called "reddit hivemind").

It contributes to a more toxic environment:

Receiving downvotes can negatively affect a user's self-esteem and confidence. Users may experience feelings of rejection or inadequacy when their posts are downvoted. This can lead to decreased participation or self-censorship to avoid future negative feedback.

Frequent downvoting may contribute to increased stress and anxiety for some users. The fear of being judged harshly by peers can create a hostile online environment.