Marimo and astral are great and we use them both, they are not however infrastructure companies, so the parallel is a bit imperfect. Wouldn't you use AWS because it's closed source? And BigQuery? Or Motherduck?

There is no "one size fits all" when it comes to building companies, and the right answers depend on many factors: it would be interesting to know your choices for example!

I do agree with you that is important to give back to the ecosystem, but per size / dollar, bauplaners have done and continue doing as much as anyone. All in all, we have shared our ideas in the community in 50+ research papers in top venues (with thousands of citations), and we have quite a few popular open source contributions, with millions of downloads and >10k GitHub stars in total (our FaaS scheduler simulator was just open sourced with our VLDB25 WS paper).

You can be a good citizen of the Python / AI / database ecosystem without doing open source as a business strategy: the reality is more nuanced I believe!