> Then you send the patch upstream, they incorporate and maintain it for you

Firing patches upstream is still adding burden to the (likely already over-burdened) maintainers.

In an ideal world, if you want a patch upstreamed, you would be contributing to upstream maintenance (or at least donating to the upstream maintainers)...

I believe both are valid: sometimes upstreams are not set up for donations, and sometimes your org will make it easier to submit a patch or to financially sponsor a maintainer.

Fair, but it is less of a burden than just submitting a report with no proposed fix. Also, submitting quality patches regularly seems to be a good way to eventually become a maintainer, provided that both sides are interested (cURL generally is – at least that seemed to be the vibe at the last year's cURL Up event I attended).