Why Is A Good Leaving Group A Poor Base And Vice Versa? Chemistry

In Organic at least, a poor leaving group, ie. Say -F, is a poor base for the same reason it left easily. Say NH3 free pair attacks CHF3, one F is knocked off but not easily since it has a strong bond to the C. Once free, F- makes a poor base as it is a small ion and it is more stable as it is. Poor leaving groups need strong nucleophiles to knock them off & those nucleophiles ie. Are much strong bases than the F- left behind or the reaction would not take place. It all comes down to the differences in size and electronegativity of the leaving group versus the attaching nucleophile.