Why all break away from Congress party vanished ??

Sharad Pawar broke away from Congress and made NCP, Mamta Banerjee broke away from Congress and made TMC and Jaganmohan Reddy broke away from Congress and made YSR Congress. Many Leaders of regional Parties were associated with Congress with one or other reason .All of them became CMs of their respective states and enjoyed power, but all of them have lost power and their parties are virtually on the verge of finishing. None of the leaders broke away from Congress on any principle, but because they wanted full control of their states instead of associating with the mother party and sharing power. Though Congress has lost many states, that too because of backstabbing by their own leaders, it is still a party which is the main opposition party in the country and it is the only party which is fighting against fascist BJP. Why not these local parties join with Congress and make it still stronger? If this happens, BJP can be defeated.