Why do we need a madhab?

Dear Brother,

The discussion at hand is that the so-called fractions/cult are mere difference of opinions and that is it… and you were saying that even Sahaba (RZA) had difference of opinions, and i agree this particular statement, even Sahaba (RZA) differed and objected on Prophet (SAAW) ( the formation of troops in the battle of Badr).. But like these major fractions we have!!! which supposedly are based on difference of OPINION, do we have any cult/fraction which is based on the DIFFERENCE OF OPINION among the SAHABA, is there any school of thought based on this very difference of OPINION? this is what i am asking…

I am sorry i was not clear, i hope i am now, the intention of the questions is to learn only…