I partially agree. I can’t understand why a leather tarp or a fiber mat placed on the (uneven) ground would be better surfaces than a table, or why a large wooden sheet would not work as a surface.
Technically you could butcher anything on the ground, but I imagine it would increase rot speed.
Maybe at one point in the development this will change again and you’d get a speed and hygiene bonus when done on a appropriate surface, but don’t need one necessarily? Who knows…