It's simply the basic rules of the market. As you bring more suppliers into a market, that tends to provide either better prices, better services, or better outcomes for the demand side of the market. In this case it's the financial institutions directly, and the consumers indirectly.
Evidence of meeting #3 for Finance in the 39th Parliament, 1st session. (The original version is on Parliament’s site, as are the minutes.) The winning word was budget.