Welcome, I had browsed r/MechanicalKeyboards and similar discussion groups and I noticed recurring pattern in user preference of smaller keyboard formats. Only reason that comes into my mind is using this additional real estate for mouse use and reduce awkward hand positioning when using pointing device.

Three months ago I decided to switch my trackball to the left side of my keyboard and after couple of days I did not noticed any serious drops in performance while I could position keyboard in optimal position for typing as well as use my right hand to operate navigational keys as well as the numpad.

Also due to the fact that I'm not exactly left handed, it frees my right hand (as well as some desk space under it) for tasks like writing, even when using a pointing device.

I would be glad to hear some input about your relationship between your mice and keyboard as well as advantages of using reduced keyboards for other reasons than mentioned above.