While most people I know who had/have summer internships did absolutely nothing prior to it in the industry and so SWs are definitely not a pre-requisite, you do want to address why you didn't land a SW. Obviously if an IB didn't bother with an application for a 3-5 day stint, they're certainly not going to bother with the same application for 10-paid weeks. You learn a lot by doing applications (the difference in standard in my CV/cover letter/application between my first application and my last is staggering) so providing you've learnt from SW applications you should be able to hit the ground running with summer and maximise your chances of landing something.