kyrios I fail to understand why a newbie would need multiple file managers while there is already one shipped out of the box
That was my first impression when I read that post. Gedit is my favorite editor by far, and anyone who knows Mousepad can use Gedit with no further training. I install it on systems where it doesn't get installed by default.
But more than that, it's a good thing to try out new and unfamiliar solutions. Familiar solutions don't require learning to use new ones, but new ones may even turn out to be much better after a bit of familiarization. For example, I just learned to configure and use the Vivaldi browser, which solved a big problem I'd previously had using Firefox to stream online videos.