That is not the case. We experimental lithic technologists have reproduced blades like those shown, used them to cut both plant materials and meats -- and have then examined the microscopic edge wear (or "polish") with the SEM [Scanning Electron Microscope].
Our results match the wear on prehistoric samples very precisely. IOW, we can distinguish whether a prehistoric blade was used for cutting either vegetable material or meat. (FYI, plant cells contain minute particles of silica, [quartz sand] the difference between vegetable and meat wear/polish is dramatically obvious under sufficient magnification.)
FWIW, I am retired, and am doing what I enjoy now -- even if that entails "going back to the stone age" on occasion... '-)