Last week, the proverbial floodgates were opened when Drupal.org finally opened access to any registered user to create a 'full' Drupal.org project (theme, module, or profile). See the Project Applications Process Revamp issue on Drupal.org for more details.
You can now contribute full Drupal projects even if you're new to the community!
I maintain many open source projects on GitHub and elsewhere (over 160 as of this writing). I have merged and/or closed thousands of Pull Requests (PRs) and patches in the past few years, and would like to summarize here many of the reasons I don't merge many PRs.
A few of my projects have co-maintainers, but most are just me. The bus factor is low, but I offset that by granting very open licenses and encouraging forks. I also devote a set amount of time (averaging 5-10 hours/week) to my OSS project maintenance, and have a personal budget of around $1,000/year to devote to infrastructure to support my projects (that's more than most for-profit companies who use my projects devote to OSS, sadly).