I honestly don't understand the point of one liners.

Really? Then I must assume that you haven't worked very much with real life data. You get all the time data that must be fixed. Like CSV data where all fields are within quote marks and your program did not expect that (or the opposite). Or simply Windows/Linux line endings mismatch. And so on.

Besides, I don't know what notepad2 is exactly, but it seems to be a Windows application. Probably not very useful when you're working on a Linux server.

To me, Perl one-liners are often a benediction to solve this kind of problems in just a few minutes.

And, just this past week, I used Perl one-liners to modify in just a few minutes all the chapters of a full book in GitHub. To do it with the find-and-replace function of any editor would have taken at least five times more, and would have been much more error-prone.