If she really capped interest rates at 15%, then some people who would qualify for cards today would be rejected. If the bill would allow lenders to choose who to lend to, it could work. However, when lenders were "redlining" the poor to keep them from getting loans, Obama and the government intervened, with a big assist from the Federal reserve continuously lowering interest rates for 30 years, and the result was the subprime mortgage industry.
Yup. She could dry up access to money for many. Make it more difficult for some more people too. Its tough dealing with the real world but we can hope the House of Reps might someday rise to the occasion.