I think it's kinda speculation we have here.
Or at least it is just a chance.
By "dual pane file manager" I don't see XY in the first 50-60 results at all.
With "file manager" XY appears somewhere on the 30th place.
It is quite understandable, there aren't more than dozen or two popular file managers out there.
And I think Dual Pane is what attracts many users, I think XY will become more popular after v8.00.
For years I was looking for a file manager, primarily dual paned, I don't remember to have tested XY before, maybe because it wasn't DP back then.
It is a matter of SEO but I don't think current results are bad.
By the way, many users look at the interface first and if they didn't like it, they won't look further.
I recommended XY to few of my friends. Two of them stated that the interface is not configurable enough, especially the toolbar is small and not dockable enough. The several panels we have in the GUI, they think should have some tiny title bar with a X for close or something. Well, this is not a shortcoming for me (even the opposite) but for them...
Give them some fancy toolbar and ways to move it around and the AB as well, and you'll win people like the two

.