I'm one of those 95%, and I can tell you that the problem isn't its lack of features as much as its overly complicated UI. Last time I gave it a try, basic tasks that take me a few clicks to do in Photoshop becomes weirdly difficult in GIMP.
You want to draw a circle? Use the ellipse select tool and 7 more steps I don't remember. You want to adjust your stroked text a little bit? You need to do the path thing from the start again.
People also love to defend it saying that I'm just "too used to Photoshop" but no, when I started using Photoshop, it wasn't anywhere as complicated as GIMP. It's a good thing we have Krita and Photopea (although the latter is not FOSS, only free as in free beer).
If you like using GIMP, then good for you. For me though, it just isn't a viable alternative if I want to get things done, even if all the features are there. :)
needs more jpeg