Why don't trading software vendors cooperate with brokers to rival MT4/MT5?

cTrader and NinjiaTrader are outstanding products in the market. But they are less famous than MT4/5. Why don’t these companies cooperate with brokers to expand market and increase their market share and challenge MT4/5?

Because cTrader is an ecn only broker which screens out all the dealing desk brokers and market makers.

Going with a broker that offers ctrader means you’re pretty much guaranteed to get excellent spreads which is good for us traders but its not as profitable for the brokers.