> there's very little evidence to support this opinion other than just wishing it was true

Building a brand doesn’t require submitting to someone else’s open source project. You can do the same thing by creating your own OSS project.

For a lot of them it’s probably a little of column A and a little of column B.

If people are submitting in their real name it’s more likely they’re building a brand. I also think it’s possible for someone to genuinely think they are helping without trying to build reputation.