One of the best articles you'll ever read on design and human behavior is John Siracusa's Strange Game. If you have a few spare minutes, go read that first and then come back.
In his essay, Siracusa contrasts his experience playing "Halo" (or any popular shoot-em-up video game) to playing the game "Journey". In the former, interactions are what you expect: lots of cursing, name-calling, and a difficult environment for newcomers. In Journey, however, the experience is altogether different: cooperation, collaboration, and a flood of positive emotions.
The key point is that it's the same set of people playing each game. Gamers are playing both Halo and Journey, but their response to each environment is completely different. And this is because people interact very differently in each. Halo (and most games) features unrestricted conversation and an open arena. Journey restricts communication to non-verbal gestures, and the only interaction is cooperation.
The heartwarming reminder from all of this is that people respond to the designs they are experiencing, and design can bring out the best or worst in us. Furthermore, placing intentionally significant constraints in designs can actually free us to engage in some of our most thoughtful and considered behavior.
When John Siracusa wrote Strange Game back in 2012, he felt hopeful about the design of Twitter to do good because of its constraint on character limits. In the ensuing 8 years, we've seen both the tremendous good that Twitter has enabled, but also the significant harm it has caused. Limiting character counts, it turns out, was not enough of a constraint.
I'm glad to hear the recent news that Twitter is continuing to evolve their thinking in this direction, with the news that its next update will allow people to drastically limit the amount of conversation against their posts. My hope is that it signals a reminder to all designers that constraints are one of our most powerful devices. When applied correctly, constraints have the ability to bring out the best in all of us.