Wherever there's human interaction, there will be politics.
On the other hand, even tho the code submitted is of high quality and good, it may have negative social effects on the projects: the feature may be out of the scope, the project owner(s) might want to make sure that the author of the patch will be there to support it because they don't have the expertise, etc. For example if I was maintaining a web server and you submitted a default mime.types file, I'd hesistate to take the patch if you said you wouldn't be able to support it, because I know nothing of MIME (sorry for the silly example).
No, it's not silly. What you said makes sense. I am referring however instead to meeting resistance in a project because something I've done or said doesn't line up with the already dug-in political interests that often exist in open source projects. I don't want to name names, but I can think of specific large projects (a couple of household names) that operate in this manner. Argue with a core dev about anything, and your PRs will get closed without any discussion. It sucks.
On the other hand, even tho the code submitted is of high quality and good, it may have negative social effects on the projects: the feature may be out of the scope, the project owner(s) might want to make sure that the author of the patch will be there to support it because they don't have the expertise, etc. For example if I was maintaining a web server and you submitted a default mime.types file, I'd hesistate to take the patch if you said you wouldn't be able to support it, because I know nothing of MIME (sorry for the silly example).