I'm sorry, but just no. That's far too strong general statement. I've done quite a bit of sysadmin/devops style work over the years, and also worked with many other people who've sent various kinds of fixes upstream. Sure, third party software isn't always easy to fix, but it depends on what the alternatives are. You probably need to do an immediate workaround as well.
I would say that's an important part of why open source have had such a strong following among sysadmins, the ability to fix things. One could even say that diving into large pieces of software and exploring issues is the most rewarding part of the job. Just don't tell them I said that.