It's mostly a received holdover opinion from the days when Gimp still defaulted to being strongly multi-windowed. The people who keep repeating it probably have

It's mostly a received holdover opinion from the days when Gimp still defaulted to being strongly multi-windowed. The people who keep repeating it probably haven't used Gimp for a while. The usability may still not match Photoshop, but at this point the Gimp UI is largely conventional for this genre of software. Popular opinions take ages to shift sadly.