Probably because that "limb" is actually a plank (as in the nautical "walk the..."), it's over very, very deep shark-infested water and the only accomplishment to date of the platoon of 'rat presidential candidates has been to mass-produce millstones.
MHO...but just consider your thought processes right now if you were set for a stint on the Democrat National Platform Committee.
1) Kill babies
2) Destroy families, churches, traditional institutions.
3) Implement Socialism/confiscate private property, kill all business.
4) Normalize/protect fellow queers, child-molesters and rapists.
5) Politicize every issue and substance known to man.
6) Ban everything including cars, airplanes and cows/kill liberty and freedom.
I'll leave a few for the others.