Probably by having a product people like to use. They never used any crazy marketing as far as I saw, so kudos to them for building something people wanted to advocate for.

by hacking the reward circuits of your brain with immediate interactions? The issue is that those are counterproductive in the long term.

The exact same reason why people initially loved Facebook and spent so much time on it?

using addiction techniques

do I absolutely really need to know that a Docker build has completed on the project channel?

Do I really care?

But it gets rewards points to those involved in that build: "Look! I did something good! I deserve a treat"