Stackoverflow also has badges and it motivated me a lot to answer questions on the early days.

It's because people often need validation to collaborate.

Maybe this is a hot take, but… I like being validated? It feels good to receive positive feedback, and a ton of my life is structured to ensure positive feedback loops for things I want to incentivize myself to do.

I’ve definitely contributed more PRs during Hacktoberfest to get a t-shirt. I’ve done Strava runs when I might have otherwise skipped a day and been excited to see a new achievement.

Here's my hot take. I work for a small company, I'm the solo programmer. Our company's code is important, so it's all private. I work full-time and it is stressful enough, and don't have interest in working longer. Because I'm solo, I don't need Pull Requests for my own work, among other things that a team needs.

Under this system, I get no badges. I appear as though I have nothing to show. Even though I have arguably done more and been responsible for more than many people with badges have. That's irritating.

I was really desperate to contribute to an open-source project in high school, specifically an iOS or frontend web one, and it was hard to find projects that I could make a substantial contribution to. Many with `good first issue` tags were not very active, and the ones that were active were hard to get my foot in the door.

I was able to do a variety of "good first" things: readme updates, typo fixes, adding small features -- but it was hard to feel really _validated_ that my work was valuable, or that contributing to open-source was an impressive thing to do, because I (felt like I was) was surrounded by engineers, and nobody ever told me that OSS was "cool", until I met a company 3 years into college who valued OSS (more than just "wow, great job, you fixed a typo!")