Am I right that the last reply on tracker, at the time of this writing, is https://winscp.net/tracker/596#c2? Am I right that you suggest to change system wide settings? Am I right the submitter of the bug tried to explain why modification of system wide settings might not be that helpful? I think modifying system wide settings is not that helpful. With firefox, and maybe newer internet explorer, you have ctrl++ anf ctrl +-. Some sites used to suggests their audience to choose from 3 possible fonts size. With office and other editors, one can change the fonts size or the zoom. With a console/teminal, you can also change the fonts size. I think the listings in winScp are similar to the contents of a web page or an office document. I too think there should be an option to change the fonts size. I think an horizontal or vertical scroll bars should also be added when the fonts size makes the window larger then the display area.
All the examples you gave are document-viewing applications. As you use them to view documents that are possibly created in a completely different environment, it's reasonable that they give you a way to zoom the view. But WinSCP file panel is closest to Windows Explorer. And that does not give you an option to change the zoom. As it displays a list using font size and face that's native to your system, not a document.