Once I saw a video review of various Photoshop alternatives. All the guy did was just draw a face and knocked a point every time something was different then photoshop. Now changing alt+t to alt+y or what ever does take time to relearn. Which yeah it is true for him that all these programs will be slower the photoshop. But photoshop would be slower for someone that spent years learning kirta and then moved over to photoshop.
Why are the shorcuts not a simple 1 to with photoshop? Maybe language barrier, maybe just random choice from developers, maybe there is some trade or patent that photoshop has. I don’t really know.
Given enough time and practice you will relearn on the short cuts, and best way to get things done with gimp and krita.