Maybe not, but you can probably write a python script to parse the (open, documented, text-based) file format of an open-source tool and perform some important action that the tool doesn't support. Or maybe someone already wrote a library that parses the file format which lets you jump straight to pulling out the data that you want.

Meanwhile, the closed source tool doesn't support your desired action action either, but their file format is binary/compressed/encrypted/undocumented for nebulous "business reasons," so you end up spending fifteen hours pushing buttons in their GUI instead.

I suspect you underestimate your ability, but even if you're not, there are many who can. Regardless, fixing a problem in the short term might not mean actually fixing a bug in the upstream source; it might just be reading through the code to figure out how things work so you can implement a workaround outside the code. That might not be possible without the code being open.