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.
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.