Too late to edit, but here's the inarguable truth straight from the mouth of the Open Source Initiative, that the term was the direct product of Netscape's desire to get people to work for them for free: https://opensource.org/history
“The ‘open source’ label was created at a strategy session held on February 3rd, 1998 in Palo Alto, California, shortly after the announcement of the release of the Netscape source code. […] The conferees believed the pragmatic, business-case grounds that had motivated Netscape to release their code illustrated a valuable way to engage with potential software users and developers, and convince them to create and improve source code by participating in an engaged community. The conferees also believed that it would be useful to have a single label that identified this approach and distinguished it from the philosophically- and politically-focused label ‘free software.’”
Open source is not open contribution. There are many examples of open source, but closed contribution, e.g. SQLite.
What you are listing is a business strategy of a company (free labor and advertising). Desires of a company are very different from an unpaid volunteer.
In projects that leave PRs unanswered, the maintainer is already unpaid labor, but contributor want him to work on the contribution. That might not align with what maintainer wants.
Edit: Personally, I find reviewing least pleasant part of dev work. Thanks to LLMs, that now also significantly more of my paid work. My desire to do code reviews in my free time is massively lower. I would rather do it myself.
“The ‘open source’ label was created at a strategy session held on February 3rd, 1998 in Palo Alto, California, shortly after the announcement of the release of the Netscape source code. […] The conferees believed the pragmatic, business-case grounds that had motivated Netscape to release their code illustrated a valuable way to engage with potential software users and developers, and convince them to create and improve source code by participating in an engaged community. The conferees also believed that it would be useful to have a single label that identified this approach and distinguished it from the philosophically- and politically-focused label ‘free software.’”