Exactly not this. Way to straw man all counter arguments before they even got any.
That being said there is absolutely nothing wrong with building a portfolio. It is 100% valid motivation. The only issue with that theory is that no one cares about your open source contributions. Not employers, not peers, no one.
What I do find fascinating tho is that fans of the most selfish egoistical companies and tech groups ... insinuate artists, open source programmers, writers or anyone else is selfish or otherwise disapponting if any part of their work involve actual human motivation.
And I'm not deriding those that build open source to boost their own reputation. I'm just much less interested in their work than the work of folks that are motivated by improving the commons (even if they get no credit).
Because, they are a lot of work. They are not hobbies or kitchen soup two hours a week effort. These require a lot of sustained effort and time, that would either takes time from your paid job, or would make you effectively work 60 hours a week which means you have no other life.
End result is that these are paid positions, so.
What they do want, however, is to not have to spend time on the thousands of AI generated pull requests and bug reports.
The current point you're making is (I think) that OSS devs don't want credit, they want to be free of spam. I, for example, host my free software on fossil and don't accept contributions at all. It's not that I don't want them, it's that I don't want the noise, so I feel like that's a valid way to distribute open source.
But when I raise that, you're saying I'm moving the goalpost. I think the goalpost is in the same exact location as it has been for the entire discussion: open source authors that don't care about getting credit and want to distribute their free software can do so without any worry about AI.
If your underlying point is that AI has lowered the barrier to entry for code submissions, making previously-viable approaches to collaborative development infeasible, that's completely fair, I just wasn't treating that as fundamental to open source development in the same way you were.
If a modern-day Beethoven were told that his work will be slurped in by a machine and he will remain unknown to the world, would it be acceptable to him? To you?
It's a perfectly good reason, but I lament the loss of people who are doing open source just to get credit much less than I would lament the loss of people doing open source because they wanted to contribute to a shared commons.
Fame only has utility so long as it gets you paid. If you can get paid without being famous, that's probably a win.
I'm not very concerned about unrecognized genius: they are all around us, and the usual rule is that we've never heard of them. I think the that's just fine.
Fame can have many good reasons. Just feeling the warm glow of adulation is plenty enough for some.