Anecdotal and late to the party, but I once encountered a bug in the Fedora installer. The installer guided me through the process of reporting the bug, including screenshot taking, including and uploading. It told me helpful tips on writing the bug report itself. I believe it even guided me on how to create an account, and so I got frequent updates in my spam account on how the bug got fixed and when and what happened with it.

Recently I tried out their new Fedora 27 release, did the same steps to reproduce the bug, and no bug encountered! I was extremely impressed, being totally new to open source and the development of it.

Your experience may have been neutral at worst, mine was super positive. I highly recommend you try! I got a fun experience out of that little tech adventure.

Wow, that's a really nice experience.

I should note in fairness that many bugs I report into Apple's black hole of a bug reporting tool also don't end up fixed. Maybe I just report weird bugs :-)

(An example of one I reported against Mac OS that got emailed as fixed, but still happens, though less frequently: Sometimes when alt-tabbing, the system will act as though the tab key were never released.)

I reported some bugs in the Wayland support for GNOME Mutter a while ago. They were all fixed in a few days/weeks.

If by "most" you mean those with just a single maintainer who works on it in his free time, you're probably right. For KDE, not so much.

Perhaps, but why complain here then? Nothing will get fixed this way.

In any case, the software is free, and reporting bugs is one way of contributing back.